According to the lists I saw both JFK and SFO DO have them (those are the only airports I've flown out of in the last two months). My guess is I just flew out of terminals that don't have them yet. I don't think that even the airports that do have them have enough to handle everyone (or they wouldn't be being selective about who goes through them). I actually hadn't seem pics of them yet (I have now - I looked it up) but I was looking out for "something different looking" and didn't see it - just run of the mill metal detectors. I suppose it's possible they were hidden off to the side where I did not notice but I don't think so.

In terms of asking why... I'm really more focused on the message of "wait, you think making porn of me that's seen by someone I don't even get to look in the eye is BETTER than grabbing my boobs? And you think doing it without witnesses is BETTER? Uh, no. You are sorely mistaken."