0. Self driving buses might work well. But I think the breakthough will begin with...
1. Taxi companies will run fleets of self-driving taxis: alledgedly safer driving, less risk of driver/passenger abuse, cheaper.
(Initially the public sector would not do that because of "joblosses". The private sector has no such qualms.)
2. Once the risk of joblosses is past, then taxis would evolve into public transport, because...
3. Private car ownership would decrease, due to:
- convenience (available upon demand, hands free, no licence needed, passenger safety, no parking issues, etc.)
- price (no inital outlay for a vehicle, electricity cheaper than fuel, no insurance, etc.)
- safety (allegedly safer drivers, road rage not aimed at other people, etc.)
4. Less car ownership leads to fewer cars overall because, unlike privately owned cars, taxis don't spend most of their time idly parked.
That might reduce public spending overall due to less congestion, less road maintenance, less accident costs, fewer traffic crimes, etc. On the other hand, some of those are revenue earners, such as parking and speeding tickets, so I don't know.
So certainly, self driving could reduce congestion, but I think it'll happen best starting with taxis and of course... it will take time.
If a society also moved to basic income, then I would imagine public transport taxis becoming part of the overall basic income system.
Sounds a bit like communism or socialism to me, but perhaps an aspect of such that might actually work.