[drak0n1c]

Not really - the vast majority of people who engage in this behavior do not notify the airline that they aren't showing up. The pool of standbys for the average flight is typically tiny or non-existent, and it's practically impossible to find a buyer for a ticket within the 15 minutes that airlines might be allowed to invalidate a paid customer's reservation and resell it.

Wasted seats on flights is a much bigger environmental problem than wasted fries.

[FireBeyond]

They do however, have a pretty sturdy belief, that despite being paid for it, you won't be showing up for the return leg (in fact, they tell you that you will be forfeiting that return leg), so they can resell it.

In fact, they also threaten the right to cancel your entire return trip, not just the segment in question.