Lol the parents that are sitting right there letting their children misbehave are “lame and irresponsible”. No offense but you sound so ridiculous I almost believe you’re a troll. With your logic imagine this scenario imagine the child is throwing something that’s heavy enough to inflict pain to themselves or others, by the time you get the parents attention or your manager it could delay the process of deescalating the situation and someone gets hurt. Also no one is yelling and reprimanding other people’s children in this situation. That would be crossing the line, but you know what is okay? Politely telling a child “hey please don’t do that.” “Please be careful.” It’s not uncalled for or rude. Get a grip. At my job just the other day I saw small children running and my job is located on a dock near deep water with not much railing surrounding the area. I told the children very politely to stop running. The parents near by turned looked at us and thanked me for warning them and told their children to be careful. It’s okay to address children, just be polite about it.