Canada

Time for a historical metrology search!

It wasn't so weird back when people lived in relative isolation without any kind of standards, and had to come up with some sort of reference that was widely familiar and commonly available.

You know, back in the Neolithic Age.

It even makes sense why that familiar set of references would get standardized and then survive up until the beginning of the Industrial Age. Beyond that point it's all driven by American exceptionalism, a.k.a. willful ignorance. What I don't understand is what happened to the cubit. Feet make sense for distance, but as a craftsman I don't want to be foot-fondling my work pieces.

Even weirder when that foot was defined based on the body of a former king of England. But, centuries later, the country that formed in a rebellion against England still keeps using that measurement, whereas England has made a lot more progress going metric.

The auto industry, mostly. Asian and European cars are metric, and imported into America in large numbers, and even domestic manufacturers have been going to metric fasteners in a lot of cases. The oil drain plug on my S10 is 14mm, for example.

I bet if you took a look at common lumber sizes you'd see they're given in millimeters, but weird millimeters. Like why 19mm instead of 20? Because 19mm is very close to 3/4".

I'm not sure about the rest of the world, but automotive wheel and tire sizes in the US are my second favorite mixed measurement. A tire's size is given in rim width in millimeters bead to bead, sidewall height as a percentage of said width, and rim diameter in inches. A 275/75R-15 fits a 275mm wide, 15 inch diameter wheel and is 206.25mm tall bead to tread.

Here in the us, sockets come in both imperial and metric. Foreign products are made with metric bolts, but some domestic made or designed stuff will use imperial. Working on things like cars is real fun because both standards are used on the same vehicle.