When I was a kid my parents wouldnt even allow us to go on overnight class trips for school ... and those were pretty tightly controlled.
I was an Eagle Scout back in the day and I knew all of the adults involved in our scout organizations. Of course, it was easier for me since my mother was our den mother in Cub Scouts and my Dad was Scoutmaster. However, we were a neighborhood organization and many of the parents participated.
There are always some parents who use it as free babysitting, but I know any behavior on the part of adults that was even remotely suspicious was dealt with quickly.