> The interesting question is how good self-driving has to be before people tolerate it.
It's pretty simple: as good as it can be given available technologies and techniques, without sacrificing safety for cost or style.
With AVs, function and safety should obviate concerns of style, cost, and marketing. If that doesn't work with your business model, well tough luck.
Airplanes are far safer than cars yet we subject their manufacturers to rigorous standards, or seemingly did until recently, as the 737 max saga has revealed. Even still the rigor is very high compared to road vehicles.
And AVs do have to be way better than people at driving because they are machines that have no sense of human judgement, though they operate in a human physical context.
Machines run by corporations are less accountable than human drivers, not at the least because of the wealth and legal armies of those corporations who may have interests other than making the safest possible AV.