Individuals may not act rationally but regulators and insurance companies with their birds-eye view will see the hard numbers and hopefully provide incentives aligned with the rational choice.
I didn't suggest that the technology should be rushed and I agree that a careful approach can save more lives. But what constitutes "careful" matters here. For example if a city chooses to offer robotaxi discounts to people with bad driving records (before some cutoff date to avoid perverse incentives) then even an average taxi fleet could be a net-benefit even though the taxis do not perform better than the general population. And that's just in terms of lives saved, not counting the other benefits of having cheap transportation.