Are you sure that's "most parents"? The ones that have a good yell at their kids in the bedroom for their behaviour are the ones you won't hear about, and I suspect they're the majority. I know I don't expect schools to rear my children.
Even worse when administrative does not have your (teacher's) back.
If you doubt that the Peter Principle still applies, spend some time in faculty meetings and check out the admins. There are exceptions, of course. But IMHO (observation) the "No more A-holes" rule is more honored in the breach than the observance.