I also believe that most stealing was done by employees finding all new ways of stealing cash and bypassing security checks and management due to the ungreatful job of being in retail store management.
The policy was simple, and the cops expected me to follow that policy. If I called them, and had failed to follow the policy, I could have been nailed for kidnapping or false arrest... the policy was pretty simple:
1. They select an item...
2. They conceal the item...
Once this occurs, you must maintain visual contact with that individual 100% of the time until they leave. If you don't, you could not stop them (they may have "dropped" it on another shelf when they were out of site...)...
3. Once they actually passed through the doors, the intent was clear and you could stop them...
The interesting part was, I had to be able to specify exactly what the item was, and where, exactly, they had concealed it.
I watched coworkers get nailed for violating this policy, and stopping people who didn't have anything on them, etc... I also busted two coworkers (security guys, no less) for stealing... I followed the policy to the letter, and I still had the highest success rate in my district...