American drivers specifically can be improved. Every other country stands as an existence proof of that.

Drivers hate enforcement, and they vote.

Drivers can improve, but they won't. They will talk about the abstract just fine, but always in context of how "the other guy" is so bad, they resist any suggestion that they might not be good either. As soon as your point out something that nearly everyone is doing wrong (as backed up by statistics and traffic safety engineers who study this) and suddenly they will shut you down. As the other reply said: drivers vote and so any change that would affect all of them is impossible.

I'd love to see better public transit, but transit is so bad for most of us that it would take a massive investment before there is any return, and half measures won't work. You have to go all in on transit before you can see any significant change - if you invest in the wrong network you won't know until a massive amount as been invested and there is no return (leaving open the question of if a different investment would have worked).

But the incentives are there. The knowledge is even there. What's left is the sum of all values.

Deaths and accidents are different measurements. Cars are much safer in an accident than they were in the early/middle 20th century.

Per-mile-driven deaths started climbing again around 2012 in the U.S., I'd wager due to the trend towards larger vehicles causing more collateral damage.