> It still costs fuel to carry the weight and slows down the boarding/un-boarding process. This is true but if we want to play the pure fairness game should so

> It still costs fuel to carry the weight and slows down the boarding/un-boarding process. This is true but if we want to play the pure fairness game should someone who is 150 pounds pay less than someone who is 200 pounds? What about a 90 pound kid? These are drastic differences in weight and all 3 humans would likely fit in the dimensions of 1 standard economy seat. Arbitrarily charging upwards of $200 USD to check a bag at the gate because your carry on personal item was 0.5 pounds too heavy doesn't seem reasonable. A lot of consumer grade scales aren't even accurate to half a pound, you may have done the work to measure it and be wrong because you don't have a high precision scale that's as accurate as the industrial scale at the airport.