When I was working for the automotive industry their models and projections suggested that ubiquitous self-driving cars would reduce the total market for cars to ~15% of its current size. As in, sales would drop by 85%. The addressable market for automotive OEMs is set to undergo a dramatic reduction in size.
Few automotive companies have a coherent plan for how they were going to survive that existential risk.
People will still be doing about the same number of miles per year, and cars will still last a similar number of miles. So if a ride share car does 10x as many miles per year we need 1/10 the cars, but they also last 1/10 as long, so it evens out.
Sure they'll get slightly more miles out of a ride share car, but the number of miles will also go up do to dead heading and because cheaper/better transportation causes prior to use more of it.
Sorry, but at the current price of Waymo rides that just can't happen. They become more expensive than leasing a car at something like 8 rides per month (as in, get into a Waymo, expect to pay $60 per ride)
If they can figure out how to really take advantage of economies of scale, and drive the costs down quite a lot -- the desirability of car ownership will drop dramatically.
Everyone I know under 40yo already professes to hate driving and hate car ownership.
Owning a car and living somewhere you have to use it for day to day everything is tedious. But the option of one for the weekend, trips out of town, into nature is ultra valuable, enough so that it's worth it to have a car sitting doing nothing during the week for us, even in a well connected large city, in a walkable area.
At present or I suspect future costs, any kind of taxi for an out of town trip (without any rail option) of 50-100 miles is way too expensive to consider, we'd sooner hire a car, if it was slicker and more convenient. But hiring a car anywhere but an airport terminal needs a trip to the hire place, and needs to start and finish when they're open to avoid spending an extra day or two of hire. Plus time taken on paperwork and insurance faff could easily be an hour.
At worst you can just pay extra to have a smaller or more luxurious private self driving taxi vs. something more like a bus, shared with others. The appeal of owning and having to maintain something like this is nil. You're not in control, there's no ownership of the driving experience, and if appropriately compliant with the law, they should all drive the same speed.
Guaranteed availability and being able to leave stuff in the vehicle would be the main draws. Even privately owned, they'll still have subscription fees.