Of course it's rude. But we don't criminalize behavior that is merely rude. It's rude to swear at someone or fart in their direction too. In public, US courts

Of course it's rude. But we don't criminalize behavior that is merely rude. It's rude to swear at someone or fart in their direction too. In public, US courts have established you do not have a reasonable expectation of privacy. Because you're in public. Someone can take photos or videos of you, whether you're in the background or whether they're zooming in on your face. Obviously if you're getting right up in their face and refusing to go away, that turns into harassment and you can call the cops. But it doesn't matter if you're using a camera or not.