Isn't this why they charge for extra bags? Because passenger bags takes up space and weight that other people want to pay for? People argue about whether that's fair or not to charge passengers for more baggage when they're already paying, but thinking about a plane being for transfer of things, we can see why they charge more.
Not really. They charge for bags because they can. They didn't used to. Unbundling was a tactic to offset the effects of fares getting lower and lower. Paying for seat selection, drinks, food, etc, all fall in that same category.
True, take Spirit for instance. Price out a flight and they look super low compared to United. However we know there isn't that much margin in air travel. So we re-bundle everything you'd get on United, plus the things I get with my status, and the ticket is the same price or more.
