Seems to me, buying an autonomous car should not absolve the owner of liability or responsibility, and the owner (or designee) needs to be in the vehicle as it is being operated. The owner has to have adequate insurance and passed a valid written exam, which would cover vehicle code and the limitations of the technology.
For car companies, it seems they should have proven the technology out with minimum 5 years of safe driving record in controlled studies (just like FDA would require controlled studies to prove out drug/devices). Basically, you are buying this tech, but you are still responsible.
Okay, but then who would pay for this? Seems like early adopters would be elderly who want to be mobile, but don't have the driving reflexes,the physically handicapped, and those who would just rather be driven than to drive and consider this a luxury purchase.
Let's say the above scenario goes for 5 -10 years, then the tech gets less expensive, and the public becomes more trusting. At that point, V2.0 is a truly autonomous vehicle that can operate without any owner/passenger on board ( you can send it to go pick up relatives at the airport.)
I can see the above scenario working, of course legal details have to be hammered out etc.