You have to remember that at the time of the civil war the US was a largely agrarian and geopolitically irrelevant backwater. It was terrified that the civil war would be the beginning of the end. So the lack of reparations was partly due to the fact that the south was (and still largely is) destitute, and partly because the north wanted a genuine reunification with minimal bad blood. Not saying it was the right choice. But it was based in logic.

Hopefully we have all learned the lesson of tolerating bigots and thieves.