1) Yes, absolutely. As a result of Therac machines being put on hold while the flaw was investigated I am sure some people didn't receive life-saving radiation treatment when they were scheduled to - that's preferable to operating unsafe machinery. And you word it in such a way as if its 3000 deaths/day or nothing and there is nothing in between - you must know very well it's not as simple as this. I suspect emergency breaking systems(mandatory soon in US, already mandatory on new cars in EU) will reduce that number close to zero long before anything with an "autonomous" badge will be allowed anywhere near public roads.

2) You can do real-world testing without testing on public roads and endangering everyone around you - which is what Tesla was/is doing - all their cars were gathering data which wasn't actually used for autonomous driving yet, but they were able to see what the car would have done had it been running in autonomous mode.

3) No, I do not believe that. I do believe that a certain category of problems has been completely eliminated by rigorous testing, certification processes and engineering practices that prevent those problems in the first place. That's not the same as saying that there will never ever be an issue with a radiotherapy machine. To bring the topic back to self driving cars - the processes should be developed that will ensure that the car cannot not react(like it did in this case) when there is person in its path - it should be physically impossible from the software point of view. If the hardware cannot provide clear enough data to guarantee that, then it simply shouldn't be allowed on the road.