Gamestop employees always steal games just because they can. They leave games on the floor, behind the shelf and sometimes forget to lock up displays. They are fully capable of doing so without being caught, and also, they never have working security systems, so I guess everything else is left up to your descisive planning if you ever want to get a game for free.
The shithole that Gamestop is [as a whole] allows more and more peope to do whatever they want.
I wager if someone (one or more people) went into one Gamestop, destroyed the displays and robbed them, there'd be more than likely a few random customers who were already there who'd absolutely love to get some free shit and gtfo!
Also note: the above actually happened; based on true events. there's no telling when it'll happen next.