In class that is good. However at lunch kids should be talking to other kids. I know many teachers/schools are control freaks and so they would do such things, but it was always evil.

Have you never been to a room full of people/children? If there aren't these 'control freaks' in the room, then it gets louder and louder until to the limit where nobody can understand anything while all are shouting. It's surprisingly fast, about ~2 minutes to the maximum/stable loudness. This 'control freaks' are the requirement to allow children to have a conversation.