I agree with Susan. I think it would have been more than reasonable for the inspector to let you prove your case, and he didn't. Now, what was so pressing for the inspector that he could not let him take 30 seconds tops, and find the ticket? If the bin is full of tickets, does that mean that most people throw their ticket away right before they get off the bus, I'm guessing it does. In that case, it might be hard to find that one ticket and may take a lot more time. But if the inspector stays on the bus for the ride,(don't know if he does) he has a lot of time.
Oh well, I suggest you keep that darn ticket next time and you should have no hassles . I wish I had more of the facts about the transportation process, it reminds me of my college law classes and having to state the Facts, Issue, Holding, and the reason for hundreds of cases.