Having to accommodate them with wider seats means fewer seats in the plane, which means much lower profitability, or higher seat prices for normal-size people.

Having to accommodate them with wider seats means fewer seats in the plane, which means much lower profitability, or higher seat prices for normal-size people. There's only so much room on an airplane. Customers consistently choose flights based on seat price, so of course airlines are going to optimize to keep prices as low as possible to get customers. For people who prefer comfort over price, there's higher-class seats. If Americans don't like this, maybe they should try losing weight so they aren't so much larger than everyone else in the world.