I'm sure that can be discussed, focusing on this detracts from the article's main point.
> I mean, what about people who are muscular?
They're completely irrelevant, this is not about people being healthy versus not healthy, this is about weight being a direct driver of costs for airlines.
> So should people who are muscular be exempt?
No, why should they be>
> Do we do it based on height vs muscle or body fat percentage?
No, "we do it" based on weight.
> Unless we consider this, there's no way to do it fairly
How's it not fair to say "baseline of Xkg total (person + baggages), surcharge is Y/kg extra"?
Would you have disabled people pay a huge amount for their wheelchair? How is discriminating based on sex or height or build any different? Some people naturally gain muscles at a much faster rate than others. What makes it okay to discriminate against those people?
Having a society where people are not discriminated against based on factors they cannot control is far, far more important than private profit.
Right now, it's unfair to the skinnier among us, where the prices for overweight luggage and overweight pax do not compare at all. People search all kinds of justification why being obese is ok and needs to receive special attention. I do not argue with that.
But: please explain to me why I should pay E100 for 3kg overweight, while the obese person on the seat next to me pays nothing for a 40kg weight difference. How is that fair?
Regarding what you call "discrimination":
It's really really easy to exempt the obvious (wheelchair etc.) from the bill. No one is asking to become inhumane or discriminate. Where did you get that idea from? This is not about private profit but about the conceived asymmetry in the pricing structure.
The fact is that irrespective of body content (ie fat or muscle), what counts for the economics of the airline is the total weight. Heavier the passengers and the luggage, more fuel is burnt, and the costs correspondingly go up.
I agree with you, however, that the 75 kg choice is pretty arbitrary. I wonder, though, if tickets online can be initially issued at price ex "weight-rate". Everyone would then stand with their luggage on the scales, and pay $k for every kilo (without any limit, per se). To me, that seems more "fair" without setting arbitrary limits that might carry discriminatory or racist overtones.
Now, you can claim that we shouldn't expose people to the humiliation of being weighed at the airport and I agree with that and thus, it might just be best to divide the added cost among the passengers like we do today.
But apart from that, the fairness argument seems deeply flawed to me. I guess that I am quite the capitalist (even though I'm from Scandinavia) but it doesn't seem fair to me to force the other passengers to share that persons extra cost.
So should people who are muscular be exempt? Do we do it based on height vs muscle or body fat percentage?
Unless we consider this, there's no way to do it fairly without punishing people for things either they can't control or would in other contexts be a good thing.