They don't quite lock it away. They give you a special pouch that locks, you put your phone in that pouch, lock it, and then they unlock it for you at the end of the show. Your phone doesn't leave you at any point.
Not trying to argue for or against that policy. But comparing it even remotely to the COVID situation you are describing (that is currently happening in a certain country) is about as self-aggrandizing and out of touch as it can get.