Why dont we pay for flights by weight?

you guysare so close to the answer I can’t believe I have to point it out.

As for-profit companies, airlines need to find ways to turn a profit for the shareholders (bitching about stock losses? You’d be happy if your portflio companies were this good).

Buy limiting weight, the airline can tackon a surcharge to bring in more money. Same as a hotel charging extra for your kid who will sleep in the same bed anyway.