You could go with a 'per head' tax but probably just have TSA sell 'elective pat downs' by sticking a little vending machine that takes quarters/dollars and spits out a pat down ticket and cut the airlines out entirely, except insofar as you'd probably want to allow them to sell them for you too. Its not like government agencies don't 'sell' things anyway, licenses and such, toll road passes, stamps, etc. A little 'EPD ticket' if you would, no harder to dispense then postage stamps, good for a 24 hour period, present to TSA if you don't like scanners, lose it and buy another or get scanned. I've no idea what the actual cost of a pat down is, I used to do pat downs on locals in Iraq from time to time and it didn't take me a full minute, even including language barriers and slowness from how infrequently I did it, so like if we're paying our pat down guys $30 an hour and giving them two minutes a person that's a whole whopping buck, there's no real security worry about people forging pat down tickets so you could just use a normal little ticket vending dealie like pay garages use. Simple, easy, cheap, and gets rid of most of the hassle, if the consumers on the whole seem to prefer an extra layer of perceived privacy at a higher cost, you've got an easy way to adjust for it.