Originally Posted by The SSK
I think you are inventing complications here. If a flight is full up to its booking limit then you will not be able to get a seat on it, whether you are trying to pay for it using cash, credit card or exchanging a flexible ticket on another flight.
Ah - that makes sense.
Effectively then, a "flexible" ticket would be one that is as good as cash paid for it if trying to rebook to a flight that has not reached the booking limit, and as useless when the ticket has reached that limit? Airline only earns anything when the passenger flies a flight?
Whereas the non-flexible tickets have the property that whenever a passenger attempts to change the ticket, the airline either collects a change fee in addition to the original fare, or else the ticket is forfeited altogether and the airline keeps the fare without having to fly the passenger anywhere?
However, it seems that the abundance of slightly different fares depending on details like flight time, the expecte loadsof airplane et cetera could make it hard to find exactly equal fares, even for a "flexible", high-fare ticket...