It's a combination of money, utilizing public transportation, for the environment, and fear of driving in my case. I can't work full-time due to being chronically ill and exhausted all the time; my part-time work covers my living and leisure expenses, but there is no space in that for a car payment or car related payments like insurance. In my small city, we have a decent public transit system which does cover the majority of this city; since the advent of buying digital tickets or passes, I have been using it a lot more to get around.
In addition, I'm a daydreamer who loves getting deep into complex constructs of different worlds; I would not be the ideal candidate for becoming a licensed driver. That's part of where my fear comes from, as cars can be used as weapons. I don't want to hurt somebody because I randomly started to daydream about a cooler place than this boring world. It just takes a moment to make a dangerous for another person mistake in a car, so I abstain from learning to drive. It's for the best, in my opinion.