Excellent points........Here is a question...........Why is injustice so unpalatable?
We don't know exactly save to say that a sense of justice/injustice and fairness/unfairness is built into us. Toddlers have it. Hell, chimpanzees have it, which is is precisely what we'd expect.
Theory of mind has to play a large, maybe even the major part in it - seeing another ape getting the shitty end of the stick doesn't impact upon me directly and immediately, but if I have a brain large and complex enough to be able to imagine how I would feel if I were in that position, and therefore I feel bad for the other ape who is in that position even if I personally am not ... there's your inchoate sense of justice. Not-me-but-I-know-how-I'd-feel-if-it-was-me - that's empathy, and that's the beginnings of justice, AFAICS.
It needn't have been this way. We could have hung on to the reptilian brain. Scared? Well, so what. Just been raped? Not my problem, I haven't been. About to be eaten alive? I'm not in that position so pull the ladder up, Jack - somebody else's problem.
But we're not like that.
Or at least, only those we regard as very badly damaged indeed are like that. The vast majority of us are fashioned differently.