Around the margins, anything is possible - even a conspiracy among regular flyers to avoid buying seats on peak flights so there'll be some empty to move up to.

Of course, the automatic assumption is that the earlier flight would have been more expensive to book on, which is not always the case.

In general, though, I have a hard time believing that the vast majority of passengers seeking to move to an earlier flight don't have some valid reason for not booking on the earlier flight to start with. We're just charging an additional fee to let someone sit in what would otherwise be an empty seat because we can.

Perhaps we should do the same for the reverse situation - charge for those who miss the "cheaper" 0-dark thirty flight but show up in time for the peak fare morning flight. Wouldn't want anyone to get away with anything, would we.....

Jim