My self driving car will drop me off right at my destination, park itself, drive itself, refuel itself (at the lowest cost), pick up my dry cleaning while I'm busy, and pick me up again, so no lost opportunity cost there. I have a garage, and I'm not hurting for living space so no need to convert it (which would also raise my property taxes).
No labor cost to handle all the micro transfers of responsibility/possession. No complex tracking, routing, and billing system required, no embarrassing privacy and security failures even with large investments and ongoing costs in that area. You don't think a family of 2 or 3 or 4 drives 15k miles a year in America? Maybe the number of cars drops from one per person to one per every other adult in a household. Maybe retirees pool their cars with their friends or share them with their working children. Looking at all the cars on the road with one person in them, I'd say we're pretty far from 1 car per household, let alone 0.
Parking cost when I'm away go down because the car can park itself somewhere cheaper (in automated facilities), or drive itself home, be at the disposal of friends/family, drop off or pick up things for me. Since in your world their are fewer cars, that puts downward pressure on parking prices. Parking facilities can be located in more economical areas, and pack cars more efficiently because they are automated and instrumented, and their own labor costs are reduced.
One of the main practical use cases for local cabs/ubers is a ride to the airport. Since my car can drive itself home, I really have no need for a ride for hire. Also, since giving a friend a friend a ride to the airport no longer a personal time investment, the odds of getting a ride from a friend increase. If you're worried about me not maximizing my 44 cents per mile, I can take someone leaving the airport home, assuming they meet my standards of reputation. At this point you're probably crowing victory, but note that is purely a highly infrequent, discretionary use of my excess capacity, perhaps less than 1% of miles driven for most people. It's more tax efficient to just swap (robo) rides with friends.
A self driving car will reduce all these onerous costs that ridesharing is supposed to save me from, plus I can earn money from it in your Renters Paradise, so I don't see any downside in owning a car. I hardly feel the cost as it is, even without driving anything close to the most economical, lowest TCO car on the market.