The statistics are from the Feline Advisory Bureau, not my vet. They are a very well respected organisation, look on their website. I have participated in research with them in the past and they are on the ball.
Honey, your cats have been lucky and long may that continue. However, cats tend to concentrate on one thing at a time, two way traffic is very probably beyond their understanding, as well as anticipating and evaluating speed of oncoming vehicles.... and apart from that, if something is fixating them across the road from where they are, they will home in on that and ignore other factors. Its their instinct. Hence you see the mad dashes they make across a road.
We don't let dogs or horses lead 'natural lives' do we? Where is the difference? With pet ownership comes responsibility for their welfare, and I believe that exposing them to dangerous situations is wrong....apart from the fact that roaming cats get into other folks gardens ..I wouldn't want a random dog in my garden, crapping and such.
Also, if you are a cat lover, how would you feel as a driver if you hit and killed - or worse, catastrophically injured someone's pet cat? I know I would be devastated.
I'll stick with my 'overprotected cats', they are happy and safe and all but one lived into their early 20's, FIP took one at 18 months but the other 12 lived long and contented lives.