Right, it’s mostly the labor economics that make them poor choices outside of dense urban areas. Self driving EV buses could actually solve that suburban transit problem, with private on demand vehicles being a “premium” option.

Self driving buses or shuttles may actually come first around planned retirement communities. Simple routes, good weather, with flexible demand.

The most expensive thing in transit service for a lot of smaller cities is paying for the drivers. If you want more shorter headways, longer service hours then you're paying a lot more for additional drivers.

Cheap, at any price. Instead we subsidize cars at many, many times that.

You can think of everything you pay for the car you are obliged to maintain as a tax you pay as subsidy for cars. With good public transportation, even massively expanded, you would keep most of that.