[Tamerlin]

The doctor has to convince the patient that the test is necessary. The TSA agent can ignore any evidence of the effectiveness (or lack thereof) of patdowns and doesn't need to obtain your consent.

And that's the critical difference here.

What the doctor does is WITH your consent, and you have a choice in the matter -- plus it's actually truly for your own good.

What the TSA does is NOT with your consent, you don't have a choice in the matter (subject of the TSA's next porn video, or sexual molestation), and it's NOT for your own good, since there's no conceivable way that it will actually improve airline safety, given that it won't have any affect on any serious terrorist attacks anyway.