What is the purpose of over-riding the supposed "opt out" policy and having people walk through a turned off machine?
It makes perfect sense in a game of psychological warfare by the government to suppress the will of people to opt out of the intrusive searches being done. What better way than to make that naughty guy that opts out walk through and thereby, in a way, submit to the machine. Otherwise, by walking around the machine, there is a sense of victory. In such a case, one thinks, “I did not submit to that machine and the unwanted xrays and pictures. I did not go through it.” By going through it, there is a sense of defeat. “I had submitted,” one thinks.