I think shoplifting shows a willingness in our society to only care if it affects ourselves. So many people don't see shoplifting as "real" theft, or a big deal, because it's supposedly victimless (which it is not). Having worked retail I can say they come from all walks of life, and the vast majority of the time they're not doing it because they're at their wits end to put food on their family table.
What really burns me is when I hear someone say that a shop deserves to be shoplifted because of "poor" customer service. That can be a symptom of thinking that everything is about them, and someone should pay if it's not. Frustration is not an excuse to turn criminal. (Not that I think poor customer service is ok!!)
We were trained to look for potential shoplifter type behaviors. We laughed when we were shown in practice because they looked so silly, or alternatively because we thought the trainer was the overly paranoid type. It's definately no laughing matter when you see someone try it for real. That's when you have to gird your loins and be as brazen as them.
We were trained to take the overly-helpful-friendly-I-saw-you-stuff-that-down-your-front-and-I'm-gonna-let-you-know-I-know-it-"oh, are you sure you weren't looking at the size 8 tangelo sunbreeze sweater just now? That's a personal favorite of mine too! You should definately try it on, but try it in green too because it would go with X better" salesperson route to them to give up the goods. If that didn't work and if it was caught on camera (sometimes people in the way blocked the view) once they left the store we'd call security who'd trail them in the mall, and activate the phone tree to alert the stores of the shoplifter. The best defence against shoplifting, aside from employee vigilance and security cameras, was keeping the store spotlessly tidy and "walking the floor" each morning to get familiar with stock levels.