everyone knows that. People pay more attention when they know you check and the most where they think you will check. the only reason for the m&m thing is it is easy to check so anyone who has heard of this will be extra careful to do that. Meanwhile the hard to check places might be ignored. The m&m work well when it came off as spoiled brats asking for something stupid. Nevermind the dangerious fireworks on an unsupported stage, those brats screamed about the m&ms.
I’ve never been in a zoo I’m allowed to drive more thln e wheelchair through. They may require extra training - I would not know