[mikeash]

Let's say you want to fly from A->B. You research prices, and you find two options. There's a direct flight from A->B that costs $400, or you can take an indirect flight through distant hub C that costs $200. Is it unethical or wasteful to choose A->C->B for $200? I think all of us would do this without a second thought, aside from willingly paying more in exchange for less hassle.

Compare to hidden city ticketing. Instead of buying A->C->B, you buy A->B->C for $200 and then stop at B. It's no more wasteful than buying A->C->B, it's just more comfortable for you. In fact, it's slightly less wasteful, because there's a possibility that the airline could give your empty B->C seat to a standby passenger.

Assuming you don't have an ethical problem with the A->C->B hub flight, why would you have a problem with the A->B(->C) hidden city ticketing flight because of waste or disutility (or indeed anything else)?

I have no problem with price discrimination. But there are good and bad ways to do price discrimination. For example, one common method for flight discrimination is to charge less for tickets purchased farther in advance. Casual travelers typically book their travel well in advance, whereas business and other travelers willing to pay more typically book their travel shortly before they fly. This is just smart business, and it ensures that people who really need it can fly when they need to, but people who are more price sensitive can still travel. And you can't really game this system.

Then you have airlines trying stupid tricks like charging negative prices for certain legs. This is just wasteful and stupid. Why should I feel in any way obligated to support this sort of price discrimination? They are welcome to try such nonsense, of course, but their customers are likewise welcome to take advantage of it. It is not our responsibility to make their pricing scheme work. They're the ones who need to figure out workable pricing schemes.