Depends on the city. In LA, yes it’s very hard to live without a car. I live in Seattle and I live car free as well as many of my friends. It’s not that we can’t afford it, we’ve just built our lives around transit and biking and the city is pretty good for it. Then of course there’s NYC, which is likely better than most European cities for transit. But you’re right that the average here is far far worse when it comes to transit and living car free or car lite.
Even in LA it's quite possible to live without a car if you live in the right neigbhorhoods like K-Town or any other centrally located one where both the Metro and buses are plentiful. LA's a huge place with varying amounts of density.
In the states if you want to live car free you can but you need to be strategic in where you live within a city. I have lived in a few from east to west coast, suburbs to urban. By selecting your place in a city carefully you can go car free or mostly car free.