Uh... Not sure you understand the situation, example: PAL charges you $50 for a ticket. If you fly, you paid $50. If you don't show, you pay the no-show fee IN ADDITION!
The cost to the airline is marginably lower when you don't fly (weight, fuel, food, drink) then when you fly, yet they charge you extra for not flying. There is absolutely no reason to charge that fee.
And the argument "they could have sold that seat" doesn't make sense either as you paid for it and they have no right to sell it again...
The no-show fee is a total scam...
I see you have not flown airlines in America. You pay $100. Then if you miss it and want to change it that will be $250