because a ticket is not really a ticket. it is more like an agreement that if you show up at the airport and the airlins is down to transporting you, they could

because a ticket is not really a ticket. it is more like an agreement that if you show up at the airport and the airlins is down to transporting you, they could go through with that plan. when you book a ticket, it says in the fineprint that you acquiring that ticket doesnt mean that you get to fly. it is more like a bank pretending to have your exact balance available at all times. in fact, they do not. they kinda bet on the fact that not all customers want to cash out at the same time, which works almost all the time except when the banking sector melts down and all customers try to cash out at once and then banks have to admit that they cant really pay you out even if they wanted to.