For all of those pointing out the statistical inefficiencies, you are correct. But we're not talking about sampling UNIX file permissions, we're talking about drugs and fake IDs. Drugs are often linked to money and violence. Fake IDs can help you commit all sorts of other neat crimes. I don't think we need to argue that breaking the law isn't breaking the law. There's another post out on the InnerTubez to argue about drug legalization.
I have a hard time believing that every false positive that got extra scrutiny was assaulted in the manner in which some have described below, but arguing that is a waste of both of our time. You're going to point to a bunch of articles tagged 'securitytheater' and scream loudly until I stop talking.
If you've ever been stopped at the airport for extra screening, you know it's annoying. It's happened to me twice. Once was my fault, because I was getting snippy with a baggage checker. Totally my fault. Either way, the TSA isn't an evil empire focused solely on cold latex penetration. They're just doing their jobs like everyone else. It just so happens that their job is often the cause of pain and frustration for the average traveller. A necessary evil, if evil at all.
In short, you're right. In hindsight, statistically, there's probably some fine tuning to be done here, and it may not be a viable technology. And to go one step further, having these cameras at every stoplight will get creepy and bad really fast. These were a fun experiment, and in the end, are most likely not going to catch the worst of the worst. I think I was just really surprised at the raw number of people who were caught trying to smuggle illegal goods despite all of the 'securitytheater.' Takes a pretty big pair to try and get drugs by the guy that can visually identify how many ounces of shampoo you have in your bag.