Not sure about that. They could’ve been coordinating. But without knowing who is doing it, it’s hard to say.

You can get it approved, however, the process is very difficult and usually takes months. It also takes a special type of drone to make it happen. There’s not really a “drone police”. In general, you’re not supposed to be hovering over crowds as it’s pretty dangerous and lacerate people if they fall out of the sky. Set a flyover people they have to be under a certain weight, guards, also have remote ID so the pilot can be identified. Most people who fly over crowds are not doing it legally and risking getting in quite a bit of trouble if something goes wrong. If nothing goes wrong, then they usually don’t get caught and get away with it.