Requirements to drive in a car dependent region have to be minimal. Lots of people shouldn’t be on the road, but there’s not exactly room for them in Manhattan, SF, or the handful of other areas where you can live without a car.
I don't know how to get there, but most people live in an area with enough density to support most people living without a car (leaving only those who need a car - plumbers for example). However it only takes a few to use a car anyway and there isn't enough demand to support the transit needed for everyone to live without a car. These areas mostly don't have traffic, so there is no real negative to using a car in those areas unless you are very poor (at which point the expense isn't choose which luxury to spend money on)
