Probably not the sort of thing you mean because you could make an argument that this is both right and fair, and I would.
A friend of mine has a daughter with 3 children. She gives money presents for birthdays and Xmas, at the daughter's suggestion. She varies them according to age, so that the 8yo gets, say $20, while the 18yo gets $50.
My friend (and I, too) reasons that when the 8yo gets to 18 he will also get 18yo sized presents.
The daughter argues that all her children should get to same sized gift, so from her perspective, it's unfair, but I doubt that she would be making the claim that the disparity is morally wrong.
I suspect "fairness" will often be a function of where you're sitting, while justice, still a fluid concept, is more universal.