They're not. In fact, they're a terrible distraction. They put everyone on edge, so it's much more difficult to spot one person acting oddly in the crowd. Shoes

They're not. In fact, they're a terrible distraction. They put everyone on edge, so it's much more difficult to spot one person acting oddly in the crowd. Shoes, laptops, and liquids rules are all reactions to a single events. Reactionary mouse traps that never get out ahead of the new mouse. I'm not even sure what benefit it is to the government. I'd be more paranoid about silent security than easily avoidable theatre out in the open.