[azstar]

I was referring to a concert (such as a symphony) or a theatre performance. There are a fixed amount of seats in the theatre (same as an airplane). When you pay for the theatre seat or airline seat for a specific date/time, the seat cannot generally be resold at the last minute if you don't use it. So, you can't go to a theatre before, or after, the performance and say "I want to use this on a different date". The theatre will simply say "buy a new ticket for your new performance date". Why should an airline just let you fly on another date. They've taken the loss for the seat you previously didn't occupy. The analogy makes perfect sense.