Hours-long waits in the security line. Ridiculous prohibitions on what you can carry onboard. Last week’s foiling of a major terrorist plot and the subsequent airport security graphically illustrates the difference between effective security and security theater.

None of the airplane security measures implemented because of 9/11—no-fly lists, secondary screening, prohibitions against pocket knives and corkscrews—had anything to do with last week’s arrests. And they wouldn’t have prevented the planned attacks, had the terrorists not been arrested. A national ID card wouldn’t have made a difference, either…