The antitheft detector has a weak link in that it can't differentiate between a single possible theft and multiple thefts. It doesn't tell the store security personnel who has the item or where it is located. That part relies upon human intuition, an additional weak link. It doesn't help that the sensors are going off all the time for mostly false-positive events. I'm sure nearly every store's staff is almost trained to ignore them unless someone is blatantly stealing an item. By identifying those weaknesses with a hacker mentaility, one could devise plans to fix the security holes. In this instance, I would say that employees need to be trained to ask all nearby customers to separately walk through the alarm zone again when a warning buzzer sounds, so they can confirm who set off the alarm.
I've also figured out how to "hack" the airport's security scheme to sneak plastic explosives onto an airplane: Buy and modify a wheelchair that is marked and aged identically to a wheelchair at the airport. You might have to remember to add a security identifier, RFID tag, or transponder if you get to an airport with that level of sophistication. Conceal the plastic explosives inside the wheelchair and help your knowing or unknowing accomplice, perhaps an elderly grandmother, into the airport via one of the nearby remote parking lots.
TSA is doing a better job at inspecting wheelchairs and other equipment that enters the security checkpoints, but the staff doesn't X-ray, check for bombs, or perform anything other than a good visual inspection. Once past TSA, let your grandmother go to the bathroom and disassemble the forged carrier. Voila! The bomb is past TSA and ready to bring onto an airplane.
Any readers freaking out that I've just told terrorists how to do this can relax. I've written about this several times in the past with no fake wheelchair security incidents to report and even sent my scheme to the TSA when it was first formed. Plus, you can do this sort of thing with a dozens other common pieces of equipment at an airport.
Also, having used my hacker mind-set to come up with vulnerabilities in the airport security systems, I was able to devise defenses. Airports could use wheelchairs built out of transparent materials so that nothing can be hidden within the tubes. They could permit chairs to be used only by trusted employees and only within designated areas, perhaps transferring the assisted person from their chair to a "trusted" chair as they go past the TSA zone.