More often than not, when visiting the parks I see a parent (or both parents) scolding their young children (including spanking, shaking, yelling, or some other unruly behaviour) while the kid is screaming at the top of his or her lungs. This type of behaviour is totally unnecessary at the happiest place on earth (DL or WDW). Granted, children CAN be a handful at times on vacation, and yes, sometimes they may deserve scolding, but I don't think the parent should be doing this in public spaces in the parks where everyone walking by can witness it. If at all, I plead with parents NOT to hit their children, but wait until they can get to a secluded area or back in the hotel and then calmly tell their children what they did wrong.
Most kids don't understand what they did wrong, so it's up to the parent to tell them, and remind them that it's not satisfactory to do whatever they did. Most times I think it's a combination of the hot weather, walking long distances, and hunger that makes a kid become unruly. We usually don't interfere because a) it's not our kid who is misbehaving and b) we don't want to be told to mind our own business by the kid's parent. Many of us don't like confrontation, but some of us can't stand the sight of someone berating their kid. The kid is only naturally curious, is a growing human being and of course he or she is going to make mistakes. I just think there is no place for this kind of thing while everyone is watching.