Airport Insecurity Features: Pre-checkpoint Shoe Testing

My colleague Wendy Seltzer has a nice post about the newest oxymoron in airport security: the Pre-screen Shoe Tester.

As we queued for the TSA belt, there was a foot-testing platform outside, where we could see for ourselves whether our shoes would beep in the screening line.

What purpose does the foot-tester serve, other than to illustrate the paradoxes of so-called security? I imagine passengers complained that they didn't know whether or not to remove their shoes, so someone decided to give them a helping foot.

But if the foot-tester device is accurate (and it'll cause more frustration than help if it's not), then it serves as an oracle, letting good guys and bad guys alike determine whether they're likely to be picked up. I stepped on and off several times without being questioned. A would-be shoe bomber could probably use a more sinister variation: If the machine beeps, walk away; try again later with cooler shoes; repeat until the machine stays silent. The tester makes it easier for bad guys to see the detection devices' limit and tailor their implements of destruction just below that cutoff.

This seems to me to be the equivalent of an Insecurity Feature, a term I picked up from Ed Felten in the context of computer security--a feature meant to make you feel more secure while in reality making you less so. I suppose the shoe tester doesn't really claim to improve security but rather convenience, but the whole shoe testing regime seems to me to be more about the appearance of security than providing actual security, especially when you give terrorists a chance to do a dry run.