Passenger weight is nearly negligible in airline terms, as you note - considering the weight of the plane itself and the cargo, a few hundred humans on board ma

Passenger weight is nearly negligible in airline terms, as you note - considering the weight of the plane itself and the cargo, a few hundred humans on board makes little difference to the fuel consumption. The biggest factor is how many people they can cram into a plane at once. The only regulation holding this back to sane levels is emergency egress - too many people in one row and it'll significantly hamper evacuations. I've read a number of articles that conclude airline seat sizing is deliberately designed to be just at the point of unbearable, to persuade you to upgrade to the next class. Frustratingly, the next class up costs at least twice as much. You either have to pony up a huge sum for semi-comfortable seating, or try and bear it. I've flown London-Hong Kong (12 hours) in Cattle Class a few times, and that is about the most I can stand.