I think there's been two things that are to blame:
- Parenting. The dictatorship of the parent is going to be a significant cause. Parents are entrusted with teaching thier children how to become useful parts of society more than even teachers. This creates the impression that "The parent always knows best". Soon that goes across to other peoples' kids too. And eventualy it becomes the impression that "adults know everything that's best and the kids know nothing, except that what adults agree with".