> Why do people pretend there are situations they can't live without a car,
Because 95% of Americans truly can't live without a car.
If you banned cars today, I could never get to work, never see my family, my child could never attend school, we could never get groceries, and within two weeks we would all become broke and homeless. This situation described 94% of the people in my city (population around 1 million)
> even a lot of people in your city do it.
Yep. ~3% of the population of my city take public bus transit instead of the public car transit everyone else uses. The bus folks spend 2+ more hours commuting every day, and have access to only about 15% of the MSA (by population), or 10% of the MSA (by land). They also pay higher rent than everyone else, for this privilege. And the cost to provide this service to them, has a TCO higher than just providing them a 'free' car in the first place.
(And, to clarify, I don't even consider this a bad thing. I get it, for kids, or elderly folks, disabled people, people who just don't want a car or whatever. It's good that the general public makes sure everyone has transportation, and it's good to spend tax money to ensure this happens. But it is by no means more "efficient" or "greener" than driving is)
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Could we "fix" this? Sure! If everyone was a super wealthy millionaire, like in Manhattan, it would be no problem. Build a whole bunch of luxury condo buildings, make everyone live in them, ban all existing public car transportation and make everyone take some LRT train/bus that only goes to the few places you allowed, is often late or broken or screwed up in some way (at the same rate that MTA is, for example). Soft-ban parenting and children while you are at it, everyone will be so busy paying off their rent they won't be able to afford kids anyway. Force everyone to re-wire their whole lives to live in your box.
And we have that in my city too. About 3% of people here are wealthy enough that they can judiciously rewire their entire life to support "car-free" living. They are hyper wealthy, so they can afford to live in the heart of downtown, in a glass condo, living right on top of their satellite office, where they pretend "banning cars is so amazing and eco-friendly" as they pay to get their shopping delivered (by a poor person in a car), get their groceries delivered (by a poor person in a car), eat at restaurants (staffed by poor people driving in via cars), and drink at bars (staffed by poor people driving in via cars).
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This is why most Americans are looking to renewable energy and EV vehicles. It's realistically the only shot non-wealthy Americans have at living any sort of sustainable lifestyle. The financial pollution from cities is just too much to handle, and has no functional workaround for real people.