Because airlines subscribe to the same customer theories that Bob does - If you can charge them for something, do it. If you can charge them more, even better. I used to work for a major US airline and whilst I wasn’t involved in the business side, we heard enough as IT people to know they were constantly looking for ways to upcharge passengers and reduce offerings to those unwilling to pay. Then Covid hit, and the ensuing inflation and fall out from Covid, and here we are. Airfare that was $250 in 2019 is now $450. Why?