I've never understood why today's security X-ray devices can't be set up so the monitor only shows objects of a particular density. A raw X-ray image shows all kinds of stuff, and aside from the privacy issue, it makes it harder for the screeners to tell what they're looking at.
As it is now, those baggage imagers have software that color-codes things on the display, which helps... why not have it so only certain materials show up at all? Maybe some explosives or flammable gels and liquids read the same as human flesh...?
When you think about it, the advent of baggage X-raying also diminished passenger privacy... there are many (perfectly safe and legal) things that some passengers would have in their bags that they'd like to keep private...
Then there's the possibility that the X-ray will reveal some valuable item, and next thing you know your bag is receiving closer scrutiny... in back, where nobody can see them stealing (it happens). You can't lock your luggage now with anything but a TSA-approved lock (they are combo locks that also accept a skeleton key)... so the baggage handlers are less likely to pilfer anything, but the TSA have been known to "confiscate" items not on the "forbidden" list.
