It doesn't work that way. Once a car is obtained, it has fixed costs. My monthly finance payments can't be pro-rated to the days I actually use the car. Ditto for insurance. In many cases, the best deal for insurance is to pay for the year up-front. Bears repeating, a year, up-front. Insurance companies incentivize this. Between those two, that's 80% of the TCO. Fuel and maintenance are actually incidentals based on usage and account for < 20% of annual ownership costs.

Ergo, it's no surprise that people want to use them as often as possible. They want to recoup value from those fixed costs. It's simple economics.

Did you not read my entire comment? I directly addressed that.

> in the context of waymo there's no effect of "I'm already paying a ton of money to own and insure a car, I might as well use it every trip"