> I think that retribution, which is of course the principal component of justice, is a key part of prisons.

One of the arguments that Foucault makes in Discipline and Punish is that prisons, by virtue of hiding the retribution from public view, can perform nearly arbitrarily heinous retributions on people. When we tore people apart in the street as punishment it was public and could provoke outrage. Now basically nobody knows what happens inside prisons.