The problem with these analogies, dgordon, is an airline seat is somewhat of a paradox - a renewable "perishable" item.

When a plane takes off with an empty seat, that seat cannot create revenue for that flight. That makes it "perishable". However, it can create revenue the following day if sold for the next day's flight, so it is renewable.

While a meal in a restaurant is, technically, "perishable", it is only so if the restaurant makes it without first selling it. The restaurant does not have to serve a steak sandwich at 11am even if nobody is present to buy it. They can wait until 12:15, when someone wants it.

I suit is not perishable. It can hang on a rack for years until it is sold. However, like an unused airplane seat, it is a sunk cost.

In the end, the airlines could make any ticket transferable for a fee, or for free. But then you have a speculative market with all the perils and pitfalls (and chance for profits) that such a market entails.

If I was supposed to come back on Sunday, and now need to come back on Monday, how do I know I can sell my ticket? And if only one person has a Monday return ticket available, and three people want it, the bidding may get close to what it would cost me to just pay the fare difference and change fees. And if it is a Sunday, how do I get that ticket to the other person? Drive to the airport and kill a few hours, hours that I need to be at another location?

The system is designed to try and maximize yields on each seat sold. In boom times, it is a powerful revenue generator. In lean times, it can still be so, but only if costs are in relation. If it costs me $100,000 to fly a 777 - I need an average of 100 $1000 seats. If I can only sell those 100 seats for an average of $500, I'm gonna get financially clubbed like a harp seal unless I can get my costs down to $50,000.