It&#x27;s called security theater because it only gives the illusion of security: there are many examples where people have successfully brought knives, guns, explosives and what have you through these full-body scanners.<p>Further, it&#x27;s theatric because the many of the &quot;dangerous&quot; items have no obvious malicious use, and the rules are totally arbitrary. I can&#x27;t bring knitting gear on an airplane, but my small pocket knife is totally fine (according to official rules, though some airport security agents will disagree).<p>Finally, any attempt at plane hijacking nowadays will cause passengers to fight for their life to prevent it. Prior to 9&#x2F;11 people would just sit still and wait to land in Cuba or whatever, but now people associate hijacking with flying into a building and will act thereafter.<p>It could actually be safer to <i>allow</i> knives and similar &quot;weapons&quot; that can&#x27;t penetrate the plane body, so people have a chance to defend themselves when some terrorist inevitably smuggles aboard a handgun and starts shooting.