Then local Gov will charge more to allow non robot cars on the road ( less wear and tear on the roads, fewer roads needed due to more reliably predictable drivers and fewer accidents).
Then lastly manufactures will get to a point that they need to simplify their production range and will pretty much only produce self driving.
lastly, culturally the demand will change. the ipad generation dont want to have learn to drive or have to spend their screen time driving. the damand from them alone will push for self driving cars.
There is a massive long tail of unusual cases that happen outside of major cities that nobody is even really trying to solve at the moment because there isn't much of a profit motive compared to dense cities.
Car ownership definitely isn’t going away. Sharing a vehicle with the general public gets old fast if you have the means to avoid it.
There are also many reasons people use cars for more than going from point A to point B on a purely transactional basis. Many professions need to leave things in the car or truck like tools or even your laptop. Having to take everything you own into every building in case the self-driving car gets called back home for service or whatever isn’t going to work.
If the cost of the Waymo Driver hardware falls to the point where it's not prohibitive for the low duty cycle of a private vehicle, I could see that eventually happening.
On the right, car ownership is deeply culturally ingrained as a signifier of personal freedom, and the notion of the government requiring that a robot drive you instead would be unpalatable, never mind the notion of no car ownership at all.
On the left, you have a generally hostile attitude towards cars in general as undesirable and to be replaced with public transport. Then there's a growing current of FSD being associated with "big tech" in general and Musk in particular that makes it an even stronger knee-jerk reaction.
Someone will own the platform that coordinate car movement, and then all cars will need to pay to get onto this coordination platform that will tell each car how to drive, which route to take, etc. Each car know what all the other cars in its area will be doing, so that mass coordination is possible. This is how you can get a completely full highway but all traveling at 65 mph 1 feet away from each other.
I suppose the solution is to seal in all roads then with high walls; what dystopian future.
China is demoing a lot of self driving cars in their suburbs however, so not core Beijing, but out in Daxing or Changping, for example. China could and will mandate self driving cars in dense city cores when they become viable to optimize traffic flow in cities that can’t really fit many more new roads. And Chinese companies are working hard to make mass produced Lidar economical, while America will probably just put high tariffs on that.
Also authorities are getting giddy when a human tries to drive on railways, so it's effectively illegal to drive in certain places where the ride sharing is the default mode of transportation. It's also very privacy focused, even though there are cameras everywhere you can just buy an anonymous travel pass that you top-up every once in a while. It also allows you to hop between rides for free or at discount.
In the larger cities they often use hyperloop, so you never get stuck in the traffic.