From a sign in the security inspection station at the What The Hack conference:

The world is an increasingly dangerous place. Research has shown that people need to get inspected to feel secure, even if the actual inspection is a complete farce. Yet as a society, we cannot hire half the population to perform bogus inspections on the other half in order to keep up with market demand for perceived security.

The sign on the metal detector was an even better statement on the effectiveness of these devices, which are appearing in more places all the time:

Of course, this doesn’t really address the security needs of the general population who feel secure if they’re not inspected, but need to see others around them inspected in order to feel secure, regardless of how effective the inspection is. Perhaps the next conference will have a DIY security booth where patrons can bring in others for inspection so that they feel safe.