The usual story is that we are careless calculators. The better story is that we are careful about the wrong things. The measure that matters is not what people say about fairness but what they do when nobody is scoring. The evidence here is thinner than the confident commentary suggests, and the honest position is a shrug with a direction of travel. It is tempting to call this irrational. It is more useful to ask what it is for.
Why it persists
Put a number on fairness and it becomes a target; put a target on it and the number stops meaning what it meant. Economists have spent decades modelling fairness as a quantity. It behaves more like a weather system. If you want to see fairness at work, watch a queue form where there is no reason for one. Understanding people turns out to be a more urgent task than changing them, and a great deal harder.
