You can get away without one, that is if you don’t mind sharing transit with violent junkies in any North American city. Transit can be down right terrifying to use these days.
=> https://en.wikipedia.org/wiki/Motor_vehicle_fatality_rate_in...
Anecdotally, in Boston the MBTA is one of the "falling apart" systems. I could still rely on it to commute to my college / job, and the worst that has happened was sometimes being late due to delays. There are certainly a lot of sketchy people, but I have never seen someone attacked or have anything stolen or been harassed myself - then again I am a man and I'm certain it's different for women.
But more importantly, when living in Boston I never had to use the train. Only when commuting. Because when I lived in Boston everything was at most a 3 mile walk. Even in the really bad weather I could layer up still get places without public transit.
Now I'm in a less urban area but it's the same: I don't have a car and rarely end up using transit / Lyft. I do get groceries and things delivered though, but my job and everything else is within walking distance.
I still agree it would be a lot better if public transit was more reliable, but I think many people in cities can be well-off without a car. Not anecdotally I know that most of the college students in Boston don't have a car (especially because there is basically no parking...)
As you point out, when you can find all of life's necessities within a reasonable walking distance, the need to own a car is significantly diminished. That's the goal that "anti-car" activists are pushing for.