Candidates A and B are applying for job X at a tech company. They'll be equally competent in the role. Candidate B has a rich father who can get him a position in Goldman Sachs paying a bit more.
If both A and B choose the tech company, shouldn't they get the same pay? B's alternative is irrelevant to what he deserves at the tech company. Obviously, if the money is important to him, he should take the Goldman offer instead.
Er. . . how the guy got the other offer, be it via a rich father, taking the trouble of applying to more than one job, or sacrificing pigs to demons is completely irrelevant.
Someone out there is willing to pay $110k for his time. Ergo, $110k is a fair price to ask for his labor.
Tell you what, let's talk about waffle irons instead of people. Say I'm throwing a giant waffle party and I need ten waffle irons. I ask around to my friends and neighbors and offer them $5 for their waffle irons, and most say, "Sure, sounds fair. Not like I actually use the thing."
But when I get to one guy's house, he says, "Well, I'd love to help you out . . . but the elementry school already offered me $10 for my waffle iron."
And I say, "$10? Don't they know they could get a waffle iron for $5? What makes yours so special?"
And he says, "I don't know. Maybe they want them clean. Maybe they want a particular brand. Maybe they don't know they can get them for $5, and maybe it's that my wife teaches there and they want to help her out. Doesn't matter. School offered me $10, but if you'll pay me $10 as well, I'll let you have it instead."
Now, you seem to be saying that $10 is an unfair price to ask for his waffle iron, and that he's greedily exploiting a competing offer to get extra money out of me. But from my perspective, the guy's waffle iron is worth $10 -- to him and to the school. They have their reasons, and their reasons don't matter. If the waffle iron isn't worth $10 to me, I should move on and find somebody with a $5 waffle iron to sell.
Things are worth what people will pay for them. I do not know an alternative sensible definition of "worth".
What definition of fair are you using such that what you're worth to someone else isn't a key consideration?