The scanners have been promoted as a key component of airport security, yet some airports have them while others don’t. There’s a scanner at one checkpoint, but no scanner at the one right next to it; scanners at some terminals, but not at others. Are terrorists that stupid? And if somebody is going to attempt to sneak a bomb through a checkpoint, it is much more likely to happen someplace in Europe, Asia, Africa, or the Middle East than it is in Peoria, Wichita, or Cleveland. But domestically is where most of the machines have been installed; overseas, they are rare.