Your logic is already off if you are looking at 250-300 million cars. There are about 310 million people in the US. Of those, 20% are 14 or under, so the population of drivers is somewhere below 248 million potential drivers. Now subtract the 14 & 15 year olds, those in prison, those medically unable to drive, those who live in NYC and don't have cars, the Amish, and.......

The number of cars is irrelevant. Passenger miles traveled or other statistics are much more useful.

I also don't get the tragic vs unfortunate reference. A single death is tragic if it affects you. Why is 100 people dying in a single plane crash more tragic than 2 people dying in each of 50 car crashes? Would 2 people dying with broken necks in bad turbulence on 50 flights be less tragic than a single plane hitting the side of a mountain?