h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I have worked for two companies where ID badges were required. (I'm not counting the places where the card was primarily a 'clocking in' card or access card). Both companies did work for the M.O.D. (Ministry of Defence, to the uninitiated), and in both cases the card bore a photograph of the bearer.

At one of these places the badge had to be prominently worn at all times. Security guards had the right to stop anyone who wasn't wearing their badge and insist on identification. Once a guard stopped one of the directors, who wasn't wearing his badge. The director produced his badge, and then asked the guard to produced his own. The guard, shame-faced, had to admit that he didn't have it with him!

At the second company, nobody bothered to wear their badge and the security guards never asked to see it. The company occupied a large site between two main roads, and had a road running through it that was often used by school-children as a short cut between the two main roads. What security!?!

This just serves to demonstrate the variable usefulness of ID badges for any purpose whatever.