If the Police had gone after them aiming to prosecute, it would be illegal here too. The kind of actions done here, howeverm are more along the lines of the patrols they take around places where minors are known to get drunk. That's not a crime either, but taking care of people is well spent police time IMO.

If, say, they had sent undercover officers to infiltrate an organization to keep them under surveillance, that would be a clear breach of the law. Looking after people, on the other hand, isn't against the law. Thankfully.