This won't work in America; not that it (or the ACLU) has stopped the government from doing this anyway.

This already goes on in at least two forms at a good number of US airports; one form of it also goes on at all US airports, particularly as part of the "brilliantly" implemented haraSSSSment process. Both of these forms implemented in the US (and even abroad for some US-bound flights) have lead to some ridiculous outcomes. If this became more extensive or "substantive" in America, the result would be like so many other things the DHS/TSA touches: an ever more wasteful and expensive dog and pony show.