There are two types of full-body scanners. Some are THz and some are xray backscatter machines.
Both technologies apparently scare the willies out of people.
Human folly is ever present. The pride people take in being able to develop and analyze the science, physics, engineering and math of these marvelous canning technologies can blind them to those things which they have not yet learned about them. The known unknowns and unknown unknowns both get highly discounted by the profane calculus of hubris and overweening intellectual pride.
"Gin Alley" -- the development of distilled spirits was a technology jump that had many many horrid side effects before society could learn to handle it. If you peruse the link to Wikipedia, you'll there be reminded that the problems with gin were on account of excessive governmental encouragement of the industry.