Long story short, my argument is this: it doesn’t matter if you reduce serious crashes from 100PPM to 50PPM if 25PPM of those are new crash sources, speaking from a psychological and sociological perspective. Everyone should know that driving drunk, driving distracted, driving in bad weather, and in rural areas at dawn or dusk is dangerous, and takes appropriate precautions. But what do you do if your car might crash because someone ahead flashed their high beams, or because the sun was reflecting off another car in an unusual way? Could you really load up your kids and take your hands off the wheel knowing that at any moment you might hit an unexpected edge condition?
Self driving cars are (presumably!) hard enough to trust already, since you’re giving away so much control. There’s a reason planes have to be way more than “better, statistically speaking” — we expect them to be nearly flawless, safety-wise.
These are -- like drunk driving, driving distract, and driving in bad weather -- things that actually do cause accidents with human drivers.