To be fair it's not a completely mad thing - the perception that the train is too full can put people off even trying, so they don't discover it's not as full as they thought.I read this as “the trains are too full, so nobody uses them?” Schrödinger’s train?
Apparently Leicester Tigers had a small problem after their big main stand opened, as people had got used to the Tigers selling every match out so didn't bother looking and hadn't realised that due to the massively increased capacity there were many more tickets available.