If you're using that example as a reason children should not be in the pits, then for the same reason auto racing should not be a spectator sport and fans should not be allowed to sit in the grandstands either. A tire could just as easily come off a car and go into the stands and kill somebody there. It has happened at Indy and at other tracks as well. If we stop doing things because something bad could happen, this sport would come to an end all together. People don't stop driving cars to work because they might get killed in an accident, and a child is much more likely to die in an accident on the way to the racetrack than in the pits once they are there.

If a track does not charge to have children in the grandstands, I don't think they should charge to have them in the pits. The long term survival of this sport depends on developing the interest of the future fans and racers. Any effort made to get them to the track and make them feel welcome is an investment in the future. As a parent and paying customer, I would suggest that you treat a racetrack like any other business. If you aren't happy with the way you are treated, take your hard earned money somewhere else.