Because people fear having their culture and race replaced by immigrants. Even if they're not overtly racist, few people wish to become a minority in "their own country."

The US is famously a melting pot, and yet we still have a bunch of descendants of white immigrants from Europe who fear that South Americans will take over; that Mexican culture will replace good old-fashioned hodge-podge Western European culture. That their language will become less dominant. That they'll find themselves strangers in their own country.

It's usually an indistinct fear. It seems obvious from the verbiage in the dog-whistles, but white European immigrant descendants don't want to become second-class.

Now, if we treated our own minorities well, they wouldn't be so afraid. They wouldn't be afraid that they'd be the ones with Hispanic cops kneeling on their necks; or that Hispanic immigrants would be living in giant homes and they'd themselves be the ones having to eak out a living as seasonal workers.

I think it's not despicable to want to preserve your cultural heritage, your cultural language, and to have your country legislated with the values you grew up with; but people react poorly when they think it's happening.

What I most despise in the Republicans in the US is that they're advocating for preserving cultural values that never existed broadly in the US. The closest subculture to what they're pushing is a return to the Confederate South: religion, and white supremacy. The Confederates got their asses handed to them, but the racist fuckers never gave up their values, most most Americans are blind to what their real agenda is. And they've been good insurgents, cleverly taking advantage of weak areas in our democracy to return power to a minority: themselves. It's been said and it's true: if America was a true democracy and we selected leaders by popular vote, no Republican under their current platform would ever be president again.

Anyway, getting back to your question: immigrants bring their own culture with them, and very few completely abandon it and adopt the culture and language of their new country. This dilutes the host country's native culture, and people are afraid of that. In the US, it's the highest form of hypocrisy, because our native culture displaced the indigenous culture, and now we're afraid of someone else doing the same to us.

The birth rates are low because of the terrible environment that doesn't support having and raising children. All you're doing is importing more people who will also barely have any children within a generation or so. Mass immigration is just throwing bodies at the bottom of the pyramid scheme. You can see this in action in Canada where housing is absolutely unaffordable, but large numbers of immigrants are brought in who have to work for shitty wages and live with multiple families in a single rental unit.

The screaming about low birth rate is because corporations want to keep a high labor pool so they can drive down the price of labor while keeping up demand for consumption.

Countries like Korea don't have a cultire of welcoming people from outside and therefor you would have so many clashes that a huge number of imigrants - which is needed - would destroy the country. There is no one here who knows how to treat and integrate those immigrants. There are no programs for them, etc. and even if you know the language you still have huge culture clashes.

A lot of Europe did so and for this exact purpose. Immigrants are net contributors of tax money and help a lot with demographics. Now however European countries have a sizable portion of their countries as immigrants and it turns out a lot of people feel like their culture is getting lost.

Add that up with corruption is more out in the open, austerity after the 2008 financial crisis generally failed as a policy and people are very prone to believe "Immigrants are to blame" and vote for right wing parties since they run on an anti-establishment platform.

The left generally believes that we need more immigrants and more social programs and so on but there has been a massive crusade on tax rates which hinders the governments ability to pay for them.

This is all coming together now and the far right narrative is being given a chance in Europe with their anti-immigration stance.

In my opinion this is basically the centre-right trying to get votes by cutting taxes, end up taking on massive debt or gutting quality of life social programs so the only way forward is to fuck over minorities and making the most vulnerable people suffer for the greater good. But tax the well-off, rich, wealth, land, capital gains, profits? Nooooo, can't do that because they fund the political parties. 🙃

Xenophobia propped up by political groups. Many official immigration programs existed in the 19th century that, when allowed to, had immigrants integrated into society.

I talked to Japanese colleagues about this a lot. The issue isn't just plain old xenophobia. In a lot of cultures, when someone gets married, there are considerations about marrying 'the right kind' for the family. As silly as that might sound to U.S. 'melting pot' ears, these could be tribal, economic, linguistic, geographic, class, education, age, gender, and yes, race.

In traditional settings, the elders have to bless that marriage, welcome the person, and ideally have the families mesh together and be on the same page.

Inviting foreigners with vastly different backgrounds on almost all those axes, it's a pretty tall order to ask everyone to change those attitudes. And saying one family should close their eyes and do it for the sake of the country while their neighbors hold out for a 'suitable' match is going to be tough. The demographic 'time bomb' has been a known issue since the 80s and people are still resistant to change.

At some point, though, realities catch up.

My bet would be it would take a generational turnover and a few years of popular sitcoms normalizing it.

Wouldn’t they benefit from more people?

The wealthy win when there's more workers than work.

Historically the greatest gains in workers rights and the times we make the most gains against wealth inequality is when there isn't a surplus of workers.

Xenophobia and racism, mostly. And yes, it's a solution to the aging demographic crisis many countries face (at least in the medium-term).

I remember seeing a video of a presentation back in the Bush years by some neo-con group that advocated for immigration to Pentagon or DoD officials or something. The argument for immigration was mostly the same: we have an aging population, so we could integrate immigrants (who are statistically younger) to solve this issue. I didn't agree much with the broader idea of the presentation though. The broader idea was that there were still some parts of the world not a part of the global U.S.-led hegemony (mostly the middle-east and Africa), and we must spread democracy and capitalism to them. The argument was that globalism/capitalism ensures peace, and that both WWI and WWII happened because globalism was falling apart shortly before those wars. So, to ensure world peace, we need to globalize the entire earth and bring all countries into the the U.S.-led hegemony, even if that means starting wars to spread democracy, lol.

It's bigotry. Whether it be racism, or classism, or political, or religious, or whatever. People have endless reasons for wanting to consider others as outsiders or lesser or different.

Because most low birth-rate countries are first-world countries, and they generally want to only accept people who can contribute to their society and not be freeloaders to the social system. This means they need to filter out the people that come in, and being first-world countries, there is no shortage of people trying to get in. Sometimes they want low-skill, not-highly educated people just for the cheap labor, but not the person actually staying permanently, hence temporary worker visas. If a foreigner really wants to stay permanently, they then need to ensure that you are educated, able to support yourself long term, do background security checks, and make sure you agree to integrate as you mentioned in the OP.

Fear of being outnumbered by immigrants ("they shall not replace us" bullshit) is a big one.

Xenophobia

Why don't fat people hit the gym and eat salad?

This is a gigantic can of worms that will cause arguments.

You have to feed and house the people. The people currently living in those countries may have a shortage of housing already.

I think the "baby boom" from years past has shown that there are too many people around. It's too costly to raise their own kids. People are xenophobic and don't want many immigrants changing their cultures.

Similar to high turnover rate at major corporations is the justified fear that the current residents will be abandoned by their own government in an attempt to drive economic incentives

Unless the system is built correctly, you could accidentally drive people away because you didn't build with your citizens best interests in consideration

For example Japan and South Korean (my heritage) has this exact problem still at large as they encourage people to have children yet systems like high working hours in combination with low wages means that people just can't afford to have children

Why would you voluntarily create a job scarcity in your own population? Immigration reduces wages, increases prices, strains public services and causes overall decrease in Quality of Life.

Just look at the state of the USA with 28% immigrant population.

Oh boy, you need so much stellaris /s