The problem isn't needing to "curb the pit riding", the problem is curbing the people who are riding pit vehicles like idiots.
There are tracks that we are pitting a minimum of 1/4 mile from the track (Red Bud, mini O's, etc) and if you need to go check the running order, buy a bag of ice, run back to the camp for a particular tool, that a pit bike does come in pretty handy.
It may be the parents that are allowing the dumb-ass riding go on the local tracks, but I can tell you that the adults at this year's Mini O's were way worse than any of the kids.
It is the same as another popular argument in today's world - is it the gun/pit vehicle or the person with the gun/pit vehicle? Why not just go after the ones abusing the privilege? Let it be known there will be one warning, the second time the vehicle gets put in a locked corral next to the gate and you can pick it up on your way out. If you don't want to abide by that set of rules, don't attend the event.
Of course if you did it that way, you would have to hire one or two pit policemen and wouldn't make any of your pit pass money.