I truly believe the reason has more to do with being antisocial than anyone cares to admit. It's not always the car's mobility that people enjoy so much as the barrier it creates from the outside world.
Socialization needs norms. It’s no accident that relatively urbanized civilizations have relatively strict codes of behavior. America’s wild and free frontier spirit, God bless it, is less fun in a crowded subway.
And soul crushing traffic is wild and free? Or suburban strip malls are wild and free? Or endless cul de sacs? There is a lot of imposed structure to suburbia too, specifically because it is planned.
In fact, it has more imposed structure, exactly because of the unreasonably restrictive zoning laws in the US. Allow more variety and you get more choice.