78 children died on the roads in the UK last year. Presumably most of them were supervised at the time.
I'm making the argument that if safety is your only priority that you would never allow a child anywhere near a road, nor would you ever let them travel in a vehicle on the roads. Please understand that I'm not talking about supervision, I'm making the argument that you can guarantee that your child will not die in a road traffic accident if you refuse to ever let them leave the house.
There is a balance to make between safety and freedom that you are being willfully ignorant of.