I don't really know how to think about it. Accident rate, on a per-mile basis, falls out of some combination of "hardness of the driving problem" (freeways have many fewer accidents than city streets, I think) as well as propensity to take risks (driving at night; in bad weather; at higher speeds; while distracted) as well as driving skill.
What, by definition, people will accept is an accident rate similar to that for professional drivers; e.g. taxi/rideshare/livery. According to a report by Uber, that's about half the number of fatal accidents on a VMT basis versus the general population in their case.
More specifically, what IF or rather WHEN there is an incident that could've been prevented by human interjection, but wasn't?
Other aspect is, why are we only ever discussing these separately? What is the safety of a automation-assisted human? Can we get to the point where safety is better than either system alone?
But for far more individuals there will be a net increase in safety, moreover, since traffic accidents don't only imperil drivers, pedestrians and safe drivers will also experience an increase in safety due to average drivers using just-above-average automation.
> What is the safety of a automation-assisted human?
That's where we're at today with systems like Tesla's Autopilot.
Reduction of average statistical risk is what really matters and will be what is primarily responsible for driving down real world fatalities and life altering injuries.
I for one am not going to stand back and let fear of new technology and unfounded preference for human driven action over automation stand in the way of making a statistical impact on reducing the 1.35 million auto fatalities that happen globally every year. To propose that possibly reducing that number to 1.30 million is not good enough and we have to hold back rollout until the tech is better than the "best driver" is disgustingly sociopathic.
Just don't stand in the way of people who choose to use self driving cars because you're more afraid of it that of extremely lethal and incompetent human drivers.