But like... are we sure we come out ahead spending decades on machine vision and self driving versus just having more human taxi drivers, and spending the money on the end goals we actually want?

Human driving cost is forever. A self driving programme cost is for today only.

The money has been spent. Waymo is operating without a driver in Phoenix, LA and San Francisco.

Ultimately it's private money. No public money is being spent on it. The government can (and should) invest in public transport also. But how alphabet spends their money isn't up to the government.

Anything can be nationalised.