[natrius]

"Is the driver really the highest marginal cost in the system? Does removing a driver really drive costs down that much?"

Absolutely. In Austin, we have car2go, a car sharing program that allows one-way trips. Gas, insurance, maintenance, parking, and any other cost you could think of is included in the price. It costs about six dollars for me to drive downtown from my apartment. A taxi costs $15.

This isn't a perfect comparison since I walk to a car2go, but a self-driving car might need to drive to pick you up. It's pretty close, though.

[brc]

Maybe the driver does add a significant cost from your example. I suspect this varies from city to city, as some cities have strict driver requirements (ie, London) while some others seem to just employ anyone with a pulse.

Another cost the car2go scheme is missing is the taxi licensing scheme, which most local governments use as a cash-cow by restricting supply and charging high recurring fees.

Add the fact that most robotic-trips are not going to be two-way and you're probably getting closer to $10 dollars for that trip, which, undoubtedly is still cheaper than with 'wetware' behind the wheel - but some people seem to be thinking this would be as cheap as mass transit, which to me is just wishful thinking.