This doesn't surprise me one bit. The police don't want to deal with the rich parent's if the kids get caught, and they certainly don't want to have to deal with good lawyers. On top of that, in the US rich people can basically give as much money as they want to politicians and their campaigns, so some of these rich people have a politician in their pocket who can give the police department shit.
It's the same reason that laws are not enforced as strictly on most college campuses.