I agree that a world of 100% fully self driving cars that talk to each other makes the road capacity and travel speeds much greater. I don't see any way, however, to get from here to there (at least in the US). Are we going to give cars to people that currently rely on beat up used cars to get to their jobs? It's the same reason we can't have single payer healthcare -- the chasm is too far for us to cross politically and economically even if the destination would be superior.