Moving self-driving vehicles requires billions of dollars of new roads to be built.
The statistic I like to use is that the train tunnels underneath the Hudson River into Manhattan move more people than all of the road crossings into Manhattan combined. It's probably cheaper in the long run to invest in better regional rail systems than it is to to keep widening highways; people drastically underestimate the costs of highway construction.
The same infrastructure that people often complain is inadequate to the task?
Self-driving vehicles are also going to come with the innovation of having zero occupants as they navigate somewhere to park. And if people want to replace existing mass transit systems with self-driving vehicles, that's going to require a lot more infrastructure.
The statistic I like to use is that the train tunnels underneath the Hudson River into Manhattan move more people than all of the road crossings into Manhattan combined. It's probably cheaper in the long run to invest in better regional rail systems than it is to to keep widening highways; people drastically underestimate the costs of highway construction.