Not sure if there are multiple models. The ones I saw had a gate (red/green, i.e. 'you can come in now' lights), and had you to put your hand down in a designated area / look into a camera.
Since I wasn't exactly able to move over and inspect the device from up close I admit that I just _assume_ that the hand thingy compares your fingerprints - I wouldn't know what else it could look at otherwise. Maybe it's just a bible and you have to solemnly swear not to be a terrorist, on camera. Looked weird from 10m away, everyone putting down their (right?) hand on the device, looking into the camera and waiting for the machine to say 'You are good to go'.
I don't plan to visit the US, ever. Personally I can easily state that I my desire to see some (probably) cool places over there isn't high enough to put up with the BS, professionally I am able to dodge any and all suggestions to go there so far - and will try to keep it that way (but that's the loophole: I won't sit on my hands and flat out refuse if my company forces me to go there. I will complain loudly and make sure that my unwillingness to go is heard though).
And the "I WON'T ANY GOVERNMENT HAVE MY FINGERPRINTS" is all fine and dandy, right until you, say, want to visit US and aren't a citizen of VWP.
Of course, you may value your beliefs about fingerprints higher than visiting some countries. Many don't. I don't.