I don't know exact statistics about the US, but in my country (Finland), it is getting very difficult to reduce the number of deaths in traffic by the kind of actions you propose.
First of all, around one fifth of people killed in traffic have committed suicide. They take their car, take off the seatbelt, and drive as fast as they can and hit an oncoming heavy goods vehicle. That's bad, because it is very traumatic to the people who drive trucks and transport stuff. They get injured physically, and even worse, emotionally. You can't stop this by making better cars; you might stop it by having only Google-driven robot cars (so we go merry round with the discussion on how evil corporations are). And even then, if people can't kill themselves with a car, they'll find something else. Next, you'll be banning pedestrian bridges.
Over one tenth of traffic deaths here are natural deaths. I.e. they are recorded in traffic death statistics, and they are used for justifying car and fuel taxes, but in fact it's the old man got a heart attack or a stroke, and died, and there's not a scratch to the car. Or just fell off the road on his bike. But it's still a traffic death here.
Then there are the tragic accidents where a child is run over by a heavy goods vehicle. Most of this is not about speed; it's about noticing people who were in a blind spot. We've had three children killed in an few weeks in this nation in similar accidents, and that is too much. Here, some automatic detection technology will probably help a bit.
But what's the bulk of traffic accidents? Mostly it's tremendous idiocy which is hard to legislate away. People who are DUI at four times the legal limit, are driving three times the speed limit, and running away from police because they don't have a driver's license, and they have no seat belts, and then they hit a tree and everyone in the car is killed.
More survivable vehicles help, and in fact the development has been huge over the past years, but particularly the people who are gross idiots are also people who drive older cars, so they are less protected.
And still, considering all this, I think road traffic is remarkably safe, and when I think how much people move around, accidents are few and far between.