It looks like something out of Total Recall (but without the Governator, obviously) and most people aren't worried about being bombarded with X-rays. No, they're worried that someone might get to see their pee-pee or similar, gender-nonspecific naughty bits.

Me? I'm worried that a voluntary scan is going to give people confidence that no one will blow up their aeroplane. Why don't we just ask each person “are you a terrorist and/or relation of Osama?” We could even automate it — “push this button if you're a bad guy” (with a big red button, connected directly to a 10,000V power source).