Instant replay has turned out to be a resounding success. Remember the Super Bowl in 2009? With just a few seconds left, Santonio Holmes, a wide receiver for the Pittsburgh Steelers, made one of the greatest touchdown catches in NFL history. He tip-toed on the very edge of the end zone. The call on the field was a touchdown, and replay confirmed the call. Imagine if he had been called out of bounds and replay wasn't available — no touchdown, and the Steelers lost the Super Bowl. Not only would we have been deprived of one of the greatest moments in sports history, but also Pittsburgh would still be reminding us of how unfair the result was. Why, they would say, couldn't we stop the game for 2 minutes to make sure the call was right? We had the technology, why couldn't we use it?
Now imagine that we don't have scanners and pat-downs and that we rely on outdated technology. Two years from now, a flight from the East Coast explodes somewhere over Illinois. An investigation reveals a passenger hid explosives in his underwear. He was not randomly selected for a closer security check. However, a scan or a pat-down would have revealed this bomb. A mother of two children who were on the plane goes in front of Congress and asks, "We had scanner technology that would have detected this bomb — why wasn't it being used?" What will you say to her?
Instant replay wasn't an instant success. It has been tweaked since its introduction, and it continues to be modified to make sure it balances the need to keep the game moving vs. getting the calls right. The TSA procedures might not be perfect, but they can be tweaked until they properly balance safety and privacy.