I might be off base but I think it's a fad. True, you could be kidnapped and cuffed where having a hidden key could be useful but stateside that doesn't seem to be all that common. Author and police trainer Greg Ellifritz extensively travels in some sketchy countries in Asia, the Middle East and South & Central America and says there it's a good idea to have some E&E gear but in the US it's probably just a fad or a Walter Mitty fantasy.