Because that's how technology evolution progresses.
Wouldn't it be fabulous, an engineer created something perfect from the lightbulb moment to full working design.
Never happens, ok rarely to be fair
Well no, it isn't. Typically we will have something that's OK, then a bit better, then a bit better.
The progression that's offered here is: OK, then a lot worse (with the promise of better to come), then a bit better.
So we have progressive improvement. But what we have here is a solution that's not autonomous, but introduces a whole load of additional risks, and then has to patch these risks with cobbled-on attention monitors, and is a total dog's dinner. Instead of going from A to B to C we go from A to D, which is a dead end but has the vague promise that it might help us get to C some day. Pointless.
Having autonomous vehicles will lead to society in general dispensing with ownership. Collosal reduction in vehicles on the road. A readily available pool of vehicles ready to collect you at a moment's notice.
It would be great if that were true, but I can't see it as a motivator for shared ownership.
What
will drive reduction in private ownership is cost. If we move toward electric there isn't sufficient raw material to make all the batteries and whatnot, so costs will skyrocket and private ownership of an under-used asset will become an expensive luxury that most can't afford.
But what about these people who have deliberately cut themselves off from convenient local services by living in out of the way locations? Well, the market will have to come to the rescue by re-opening services that have been killed off by car culture. For example some friends of mine live the bucolic idyll in the middle of nowehere. We sometimes stay there dog-sitting, and the nearest shop is a crappy petrol station that is about two miles walk away. There are no buses. It's awful. But there is what used to be a thriving village just next door. Now there are no shops there. But commercial pressures could lead to local services returning.