Just kidding—it isn't.

Four-and-a-half years (most of it spent in long security lines) and umpteen billions of dollars after September 11, the Transportation Security Agency has implemented effective security measures to prevent dangerous materials like explosives from getting onto our nation's airplanes.  According to their website, anyway.  According to federal investigators who recently tested those security measures, problems remain.

Such as, they have a slight problem stopping bombs from getting on airplanes.

To be specific, investigators from the Government Accountability Office tested security by deliberately trying to smuggle explosives and other bomb materials through security checkpoints at 21 airports.  Successful smuggles: 21.  That's a smuggle-success rate of approximately 100 percent.  Put another way, it is a smuggle-detection rate of zero percent.  Or, dollars spent per bomb found: infinity dollars.

Quote from NBC News:

In all 21 airports tested, no machine, no swab, no screener anywhere stopped the bomb materials from getting through.  Even when investigators deliberately triggered extra screening of bags, no one discovered the materials.

Quote from the chairman of the 9/11 Commission (you remember them):

I'm appalled.

Quote from a TSA spokesman in response to the NBC report:

[D]etecting explosive materials and IEDs at the checkpoint is TSA's top priority.

Quote from me:

Hey spokesman dude — your "top-priority" efforts have resulted in a zero-percent success rate.  How are the other priorities coming along?

So, tell me again: why are we all standing in those long lines?