I doubt that the airline could demonstrate that it actually lost money simply because you, one individual, failed to show on a particular day at a particular time. Your challenge is clever because it is designed to produce precisely that answer.

But if the airline reduces no shows across its entire system, it reduces the complexities of its systems. It has the opportunity to match capacity more closely to sales. It can reduce its overbooking levels, which means that less time and money have to be spent on managing that. That also reduces the amount they spend/give away to people playing the bump game.

My impression (not being in any form of management) is that the airlines are looking to make efficiencies of perhaps a handful of percentage points in these areas. The companies are so big, though, that this could have a real effect on the bottom line.

The other effect is this. The airline pricing model is designed to tease out of people exactly what they are prepared to pay for their variant of the product, out of all the different variants that are in the market. If you object to the new "anti no show" rules, the airline is basically challenging you to decide - do you want the flexibility of being able to no show, and how much is it worth to you? Some people will accept the new rules because they don't need the flexibility, but the airline then loses nothing.

If you do need the flexibility, and you are prepared to pay the extra money (even under protest), you were obviously prepared to pay more for your ticket than you were previously paying. The airline has, through the new rule, got you to pay closer to that figure, rather than you having advantage of the same discount as people who don't need the flexibility.