That's really just a negative externality of inefficient suburban development. If the 'burbs didn't exist in the first place, there would be no need to subsidize their barely-used mass transit services.
"That's really just a negative externality of inefficient suburban development." Shouldn't public transit cover rural areas and small towns also? Or is the only way to get an efficient transport system to have the entire world living in huge urban centres? Personal mass transit could allow a much wider range of city sizes to be served with relative efficiency.
Mass transit doesn't need "huge urban centers" and indeed can and does serve cities of all sizes. What it requires, though, is a minimum density. You can't serve a small, sprawling city. You can easily serve small, compact cities. Compare, for example, the transit effectiveness between Zurich and Tulsa, cities of comparable population.
Especially if you can finally get high-occupancy vehicles right. Something closer to a 6-passenger vehicle with bus-style seating... if we're very lucky, only with people at most one indirect hop away in your social network?
What? No way, trains/metro are an awful system that needs to be displaced by robot cars as soon as possible. A train is a large vehicle taking a lot of people to somewhere that no one wants to go. A robot car can pick me up at my door and drop me off at the front door of my job. It would only need to drive when there are people who want to go somewhere instead of "every 15 minutes regardless of how few people use it".
Small, on-demand personalised mass transit has the potential to be the most efficient transport system.