The number of people who die every year in car accidents is so massive that any big regulatory hold-up for automated cars, which would almost without a doubt reduce deaths by at least an order of magnitude, is politically untenable.
It may be _logically_ untenable. But certainly not politically...
I don't know about US but there majority of fatal accidents are the results of deilberate misconduct, i.e. someone doing knowingly stupid things. Unless self-driving cars become mandatory they will help very little in this regards, because road hooligans won't be their target market.