I believe that relying 100% on technology is a mistake. I also think that 3D scans are a mistake due to the controversey. There are two types of scanners- millimeter wave and backscanners. Millimeter waves produce the ugly 3D body images where they can see all your flab and argumentatively your privates. The other type, backscanner produces a 2D image, much better imo. If you read this
Newsweek article- Man vs Machine it makes a really good case how our security is mostly reactive. Guy tries to put explosives in shoe, all shoes come off, etc. Terrorist tries to use liquid explosive, all liquids come out of suitcases... The article pushes for more like something Israel does for flights into and out of their country, focus on the people, ask questions. The significant question is, is this workable with huge numbers of people at congested airports?
I passed through security today and TSA had up a poster showing this image even though what they had there was a millimeter wave machine:
This is the kind of image you get through the backscatter machine. This is their attempt to show you that what they see is not really a big deal. What they don't show you is this image for a millimeter wave machine:
picture link
This is the ugly one, imo the one they don't want you to see, the one that would cause a fuss, because you are being seen basically in the buff. They need the software to produce a generic body and add in the foreign objects. This would fix the controversy imo.