Security is both a feeling and a reality. The propensity for security theater comes from the interplay between the public and its leaders.
When people are scared, they need something done that will make them feel safe, even if it doesn't truly make them safer. Politicians naturally want to do something in response to crisis, even if that something doesn't make any sense.
Often, this "something" is directly related to the details of a recent event. We confiscate liquids, screen shoes, and ban box cutters on airplanes. We tell people they can't use an airplane restroom in the last 90 minutes of an international flight. But it's not the target and tactics of the last attack that are important, but the next attack. These measures are only effective if we happen to guess what the next terrorists are planning.
If we spend billions defending our rail systems, and the terrorists bomb a shopping mall instead, we've wasted our money. If we concentrate airport security on screening shoes and confiscating liquids, and the terrorists hide explosives in their brassieres and use solids, we've wasted our money. Terrorists don't care what they blow up and it shouldn't be our goal merely to force the terrorists to make a minor change in their tactics or targets.
Our current response to terrorism is a form of "magical thinking." It relies on the idea that we can somehow make ourselves safer by protecting against what the terrorists happened to do last time.
