It's clear that people value fairness, even to their own detriment. In a game called "the Ultimatum Game", one participant is given a sum of money by the researcher, say $10, and told they can split this money with an anonymous second player in any proportion they choose

The catch here is that it is free money. If the participants had to work for it, even a little bit, I bet that the sharing level would drop significantly, to the lowest level they think they can get away with, whatever it might be.