The US still hasn't finished industrializing/urbanizing, so we still have relatively large rural populations that drive longer distances to go to and from stores schools etc. The schools can't even cover the area they serve with bus service for children. Those areas will continue to meed cars, and they aren't a corner case, they are still roughly a fifth of the population.

And buses dont work that well in suburbia and that is over half of the population. Only about a quarter of the US lives in denser urban environments.