Justice is not revenge. The instinct that wants someone to pay is old, strong and easily mistaken for a sense of fairness. But justice asks what's owed and what repairs the situation, which frequently isn't the same as what would satisfy you. When "justice was done" means "they got what was coming to them," something has usually been substituted along the way.
Fairness has four parts, and the obvious one matters least. Researchers separate the fairness of the outcome, of the process behind it, of how people were treated while it was delivered, and of the explanation they received. The finding that ought to change how you work: the last three matter most exactly when the first one is worst. You cannot out-pay an unfair process, and a good outcome delivered badly can land worse than a bad outcome handled well.
Equal and fair are not the same word. Treating everyone identically is simple, defensible and often unjust — the same rule applied to people in genuinely different situations produces different results. The harder version requires you to distinguish between the differences that ought to matter and the ones that shouldn't, and to be able to say out loud which is which.
The unfairness that gets your attention is not the largest one. Someone might mildly disapprove of a young person who doesn't give up a seat on the bus and do nothing about it, then be consumed by the injustice of a scratched car in a parking lot. Attention follows proximity and self-interest, not scale. Justice starts by noticing that your own outrage is a poor measuring instrument.
That's what justice is — not making sure people get what's coming to them, but making sure they get what they're due, by a route they can see.