Funny, I've never heard of a passenger getting busted for being light fingered following security. I suspect that few, if any, passengers go through security with the requisite boarding card and ID with the intention of nicking something. So it would be more chance opportunity that might occur once in while.
Even a dedicated black hat is going to think twice about taking something that is not his/hers as being caught is going to disrupt their travel.
On the other hand minimum wage security gorillas have opportunities that no passenger is ever going to have. You quite often hear of them being caught as well. Less so in Europe, likely because they can earn a living wage here.