I guess you don't use planes either? After 9/11 it's a stupid and dangerous idea.
As much as I don't like the TSA, they're a lot better than venue security. Going on your anaology, if something happened in an airport past security, the airport isn't blocking your ability to call for help.
Bringing it back: What benefit is removing people's abilities to use phones and smart watches going to give you? (Yes, they remove both of those including fitbits)