My experience is the opposite - kids have a natural sense of fairness, which is of course heavily bent by self interest. Assuming you yourself are not transparently full of sh_t, you can usually get them to appreciate your position if you can explain it to them on their level.
Adults, having the advantage of decades to cultivate our twisted bonsai tree neuroses, can be literally impossible.
Some of this can last into adulthood—a common problem for small business owners and contractors is charging too little, because they know their costs and time and what a fair price seems like it should be.
They have to have that innate child’s sense of fairness trained out of them. The notion that “what the market will bear” is fair rather than (often) screwing people over is something that has to be taught, more often than not, from what I’ve observed.
Adults, having the advantage of decades to cultivate our twisted bonsai tree neuroses, can be literally impossible.