LP, your envelope calculations are probably a bit simplistic,but theoretically you’re in the ball park.
For me, it’s time for yet another metaphor. Airlines ,with a few exceptions have changed their attitude to us. Blood and stones come to mind,driven by greed, yet we grudgingly accept paying for things that used to be provided as part of the service. .
Why we as consumers accept it defies logic,but we do,and this just encourages the bean counters to recognize even more bizarre ways to screw us over.
Just look at the charges that BA have euphemistically marketed as added benefits……
Paying to guarantee seats together
And,by the way I’m not having a go at BA,…..EI & KL plus many more are just as culpable as the culture of shareholders greed replaces a great customer service experience.