[throwketchup]

> There's a significant background check involved which, I suspect, does more to enhance security than some millimeter wave scanner in the security line.

No, there isn't.

I walked into the interview booth on a whim one day, when my flight arrived early. They were booked solid, but someone had missed their time, so they slotted me in. My "extensive" background check was completed and KTN issued in less than 24 hours. They may run some sort of cursory criminal records check, but any such check is automated and too fast to be called "extensive."

Edit: I should add that I do not have (and have never had) any sort of security clearance, but people who do tell me that the process for the lowest level of "real" security clearance takes many months and costs many thousands of dollars.

[zzalpha]

That really depends on the partner program.

The Nexus program in Canada, for example, involves among other things an extensive interview and background check by the opposing country (for example, as a Canadian, the US performs my check).