The thing about those 40K deaths is we could already avoid a huge percentage of them with relatively small interventions like speed cameras and daylighting. The fact that we choose not to do this is a real indictment of our society. Nobody, and I really mean nobody, was willing to inconvenience drivers to save those people before self driving cars. So I am not sure why they'd be willing to inconvenience drivers after. The revealed preference of America is that inconveniencing drivers is never worth it no matter what.