Right, but with a self-driving taxi system you don't need a discrete car per person that's only used for transit in and out of the city. You can use fewer and r

Right, but with a self-driving taxi system you don't need a discrete car per person that's only used for transit in and out of the city. You can use fewer and reuse them over and over and over again during the course of a day. This is both a more flexible and more robust system than trains. Plus, given a grid system like Manhattan, blockages can be routed around. People don't seem to believe me, but we're all on the internet aren't we?