Public transportation sucks at a fundamental level. It's a graph with an extremely limited number of nodes on a completely fixed schedule. That's clearly inferior to free travel from any point to any point.
Given equal travel time I'd pick an autonomous car over train or bus 100% of the time. I'd pick a self driven car 100% of the time when not inebriated. For the most part faster travel time in a train or bus isn't a sign of their superiority but a sign of failure in proper infrastructure for cars. =I've been throughout Europe. Including two weeks in Vienna. I still think public transportation sucks and asking for more is asking for a faster horse.
In the United States I'd argue there isn't a single city with good public transportation. Not one. Some folks will list NYC as a good example. I don't consider a city with the single worst commute time in the entire country as a positive example. [1]
[1] http://www.bloomberg.com/visual-data/best-and-worst/longest-...