I take you point in part (justice is the stronger version) but fairness as you describe only occurs in social animals which actually do have a more complex definition of fairness than simple equality. Chimp ‘morals’ would include the notion that high status individuals “deserve more” - which I think is simple moralising which goes beyond equality
I think we have a disagreement here. Justice and fairness, in my view, are two distinct categories. Fairness is not always just (e.g. separate but equal), and justice isn't always fair (e.g. affirmative action). There's occasional overlap, but the overlap is incidental, not contingent.
