Do you never get on busy trains? As someone who often ends up sat on the floor, this is usually what happens- people get on the train, they avoid the empty reserved seats because it's embarrassing for all people concerned when someone comes along and tells you you're sat on their seat. You walk past unreserved seats with bags on, again in a desperate attempt to avoid the embarrassment of asking people to move their shit, hoping to find another empty seat in the next carriage to avoid any form of social interaction. You then try the next carriage (at this point you're thinking "shit, I should have just asked that wanker to move their bags"), onto the next carriage and.. SHIT! It's the the last one and it's full. You turn back hoping to find one of the earlier empty ones but crap, the corridors between carriages has people stood up- there must be no seats anywhere! Resigned, you slump onto the floor. About half an hour into the train journey, the guard pulls off all the reserved tickets that aren't taken and starts telling the people who are standing that there are seats further down. They tell people to move their bags off the seats. It's not fraud or incompetence, it's just how trains work.