Originally Posted by
Abrahn
If that's the case why does the machine insist on you taking your glasses off?
At UK airports, most of the time the machine "asks" me to remove my glasses... but sometimes it doesn't. I've never been able to figure out why. I assume there might be some degree of "randomality" (if that's a word) built in, just to provide a slight extra level of unpredictability that someone with nefarious motives might not be able to rely on 100% of the time.