It has a lot to do with the parents. Let your kids out, let them explore, let them walk to school.
Statistically it's safer for them to be out on their own now than it was 30 years ago. Set an example for your kids, get active.
The world is a dangerous place, we're all going to die...someday, in the meantime get out there and enjoy life. What are we saving ourselves for? It doesn't get easier to ride when you're old...trust me.