It's a good concern to have, but I also worry about waiting too long here. At the end of the day, there's going to be problems that the testing would have never found regardless of how much testing there is, and we need to be psychologically prepared for that.

It took airplanes a long time to become safe (through a long and scary process), and now they're safer than my front porch. Whatever the outcome, self driving cars will very likely be safer than human drivers, and that means more lives are saved than lost, even with the occasional horrific problem. It is entirely plausible that self driving cars are already safer than human ones.