And how much good has that done when anyone can drive them whether they do so legally or not?
I don't know how to put a number on it. TCM offered this:
To give a little clarity traffic has become much more heavily regulated since 1921 when we have the first figures for road deaths per million miles traveled, it was at 24.09, in 2013 it is down to 1.11. that over a 20 fold drop in the dnager on roads in the US since 1921.