Having worked as an assistant manager of a movie theatre back in the day, this doesn't surprise me too much. Lots of people around and unless the operator is around frequently, most employees would probably assume they are who they say they are...
One of our competitors Theatre was robbed by a guy who dressed up as a manager, went behind the concession stand and told the employees he was the new assistant manager and he was just doing his mid rush cash pull. He obviously knew how the theatre operated, and to do it in the middle of a weekend rush, when everyone is too busy to pay attention.
I guess it could happen to any pin in a public place.
Sorry to hear it happened.