I've spend a good deal my adult life around bikers of all types. When these people have kids, they are naturally going to encourage them to follow their interests. I've met loads of kids who ride quads, scramble bikes, go carts - you name it - with no problems. The difference is that parents in this case are aware of the dangers. Kids are taught properly, steadily, and are taught to have respect for these machines. At competitive events and rallies, safety is paramount - if a kid doesn't have the right protective gear, or if they break the basic safety rules (like messing about in the paddock, for instance, or bad racing practice) he or she doesn't take part. Period.
What results is a healthy, family social activity where kids are valued and included. Most of them grow up to become safe and sensible road users because they know what happens if you ignore the rules. It's people like those involved here and in the cases Katie and Legend cite that bring the weight of the 'too dangerous' brigade down onto those trying to do this the correct, safe way. That happens and we all suffer.