Airlines don’t like no-shows — when a passenger with a reservation or a ticket doesn’t show up for his or her reservations.

Carriers try to combat this issue by overbooking flights; an inexact science that can be messy. Overbooking may result in passengers being bumped and others waiting until the last minute for seat assignments. One would think that airlines would do everything they could to minimize the problem.

However, current policies at most major carriers actually exacerbate no-shows. Passengers often miss flights either from neglect or deliberate payback. Here’s what I mean:

These days, airline change fees for legacy carriers are $200 PLUS the airfare difference. This means with any fare less than $200, it’s best to walk away.

There are plenty of such fares, even roundtrip. Most recently, I worked with ticketed passengers to Seattle and Los Angeles roundtrip from San Francisco, where I had to explain that the “credit” they would receive by canceling their flight would be nothing.

Even more frequently, a passenger might want to change a return flight. If they haven’t already started traveling and flown the outbound leg yet, legacy carriers will generally require that the whole fare be recalculated. Meaning, say on a cross country flight, even if the new return is wide open for the same fare, it may cost hundreds of dollars more because the outbound flight has either become more expensive or because the passengers have lost the advance purchase benefits, even if they don’t change the outbound reservation.

In the roundtrip situation, an airline may allow the passenger to change just the return for $200 once they’ve traveled on the first flight. Of course, by then, the return may have sold out.

So, I’ve often suggested that clients just buy a new return ticket and toss the original away. Change fees imposed make changes to airline tickets uneconomical.

Even what seem like the smallest of changes may result in a situation where the original ticket has no value. One client, a 1k member of United’s mileage program, had a roundtrip ticket from New York to Las Vegas, returning from Burbank via San Francisco. (He was driving with a friend to keep them company.) The ticket was booked two months in advance. Eight days out, the friend announced that he couldn’t make it.

At this point, the only ways to get to Burbank to make his flight to San Francisco, and then back to New York, short of renting a car and driving 4-1/2 hours, was to take Southwest from Las Vegas, with a long connection.

My client was willing to buy a United ticket from Las Vegas to San Francisco, if United would let him just cancel the Burbank to San Francisco leg (which also means they could have resold that leg). No chance. Even with his status it would not only be a $200 penalty, but a fare recalculation that would bring the total fare increase to over $500 — for not taking a flight.

If someone were doing a connection to circumvent fare rules that would be understandable, but the original return ticket was barely over $200, and would have been about the same had he booked San Francisco to Newark in the first place.

The examples go on. But the results often end up the same. An advance-purchase ticket is valueless should any changes need to be made. The only reason to cancel the reservation is courtesy to the airline and standby passengers or, maybe, karma.

Many travelers no doubt decide on some variation of “stick it to the airline.”

This revenge option doesn’t just cost potential lost revenue from the booking. If a traveler is an elite level flyer, as many frequent travelers are, they might have a seat assignment that could be sold for $100, or more, over the regular ticket price.

If a traveler no-shows, that seat only becomes available for other passengers at the airport minutes before departure. By that point, it’s often too late to charge extra. Plus, it’s more work for the gate agents.

How could airlines remedy this situation? While airlines could try more punitive measures they might be difficult to enforce. (How do you bill someone for not using something they paid for?) A more logical solution might be simply to make the change fees, say, half the price of the ticket.

Or, airlines could give more discretion to individual agents. Often airline employees have agreed with me completely — they could resell the reservation or at least the seat assignment to make the airline more money, or make the customer happy by transferring them to their preferred flight that might not be full, etc. But, their hands are tied.

Maybe in time the legacy carriers will figure out a consumer-friendly solution that also helps their bottom line. Until then, angry travelers will continue to ask themselves, “Why should I help them out?”

I don’t blame them.