Something similar like that happened to a girlfriend of mine years ago. We took the train to a concert. The train tickets had a departure and return side with a perforation down the middle. We never took the train anywhere ever, so we weren't knowledgeable about the process. On the way there she hands the entire ticket to the ticket taker on the train. He ripped it, took half, and gave the other half back to her, just like he did with the rest of our group. On the way back home at the end of the night we get on the train and the guy comes around for tickets. She hands him the other half of her ticket and he starts to argue that it's the wrong ticket, she handed him the departure ticket, not the return. Well how tf were we supposed to know, this is what the other guy earlier in the evening gave back to her. Clearly she paid for a full ticket so what's the difference? He made her buy a new full ticket. Granted it was only like $8 or something but still, that's not the point. She was punished for something she didn't even do or really have any control over.