The TSA will say, "Oh, we're not allowed to talk about successes." That's actually bullsh*t. They talk about successes all the time. If they did catch someone, especially during the Bush years, you could be damned sure we'd know about it. And the fact that we didn't means that there weren't any. Because the threat was imaginary. It's not much of a threat. As excess deaths go, it's just way down in the noise. More than 40,000 people die each year in car crashes. It's 9/11 every month. The threat is really overblown.
It's politics. You have to be seen as doing something, even if nothing is the smart thing to do. You can't be seen as doing nothing.
Popular Mechanics: It's "security theater" designed to make it look like the thousands of TSA government workers are doing something useful.