ORGANIZED CRIME AND RETAIL THEFT
Apparently, organized crime has made shoplifting far more efficient. They sometimes have special bags that confound anti-theft sensors. Shoplifters also work in groups to help distract the sales people. You can find an article about this problem here.
There are few guides available online to assist retailers with this problem. One of the few that I could find is located here.
Finally, I found a booklet from Price Waterhouse Cooper that discusses how Canadian Retailers are currently addressing the problem. You can read it here.