Pure speculation but if it is indeed more expensive, it may be to avoid the perception that they're competing with human ride-share drivers.
I think that is very wise to avoid that political minefield by making it a little bit more expensive until it's actually production ready.
I wonder if it's also possible Uber and Lyft dropped their prices in the area. Also to be fair, you don't feel any pressure to tip in Waymo either.
I read somewhere that each vehicle cost $250k because of all the hardware
Surely, though, the cost of operation has little to do with the cost of rides? Google has poured billions into the project. A few dollars per ride isn't helping their accountants sleep any better.
Hardware costs are dropping pretty fast. Lidar is already an order of magnitude cheaper and compute benefits from Moore's Law.