Seems you got my point. We arrest parents for leaving their kids in a locked car in a parking lot. But strapping them in a steel cage and letting them hurtle around a race track with others is somehow okay?
The fact that there are occasional fatalities doesn't make it a dangerous activity. There aren't black and white categories of "safe" and "dangerous". Some things are just riskier than others. For example, most parents run similar levels of risk with their children's safety when transporting them from A to B by road, or teaching them to ride a bike, than they would take by allowing a kid to race mini stocks. It's just that when a child dies in a road traffic accident we don't hear about it.
A level of risk is accepted. Motorsport used to be extremely dangerous, partly because technological advances which now mitigate a lot of risks weren't available then, and partly because the sport didn't do enough to get rid of easily avoidable dangers.
There is always more to do, and further to go, in making improvements and advances and getting rid of avoidable danger, but by now, motorsport is not especially risky when compared to a lot of other things an active child might be doing with their weekend. A parent would have no rational basis, therefore, for singling motorsport out as being too dangerous an activity for their child. They would have to keep their child away from a lot of other activities as well, and a kid has to be able to live his life.