The problem is, if it gets to production, the first real accident will be considered totally inacceptable.
It doesn't matter if you reduce by a 1000 the risk of accident. When an accident is caused by a human error you have someone to blame, you can think "I would have done better". But when the accident is cause by a machine, then people will stop trusting the car and be done with it.
I've seen this argument made in many forms. The short response is: "Google already thought of that."
People will be upset, even outraged, by the first few autonomous car accidents. But as long as they're still legal, they'll be building up a safety record that will quickly surpass what humans can achieve. Google has already invested enough money in the legislative system to prevent laws from being yanked off the books after one accident.
The general form of "People won't like it when machines do X" doesn't have a lot of merit. There are always problems and people never like it at first. Then they get used to it and quality of life improves over time. I'm sure similar arguments were made about the automobile itself.
It doesn't matter if you reduce by a 1000 the risk of accident. When an accident is caused by a human error you have someone to blame, you can think "I would have done better". But when the accident is cause by a machine, then people will stop trusting the car and be done with it.