For Marxists there is of course a contradiction here. We see capitalism as history, not as evil. Yet most who join the struggle do so out of rage at injustice ("evil"). But it is only a nominal contradiction. Most of those who make a revolution are not revolutionaries. Most revolutionaries are not Marxists. Marxism (as differentiated from the personal thinking of Marx) is the analysis of an abstract capitalism, and it is in analysis that it is crucial to put aside all moralism, all appeals to some founationless Good. (See Ollman, et al). The moral outrage against injustice which rallies millions to the cause of the oppressed remains a simple historical fact, not requiring "philosophical justification."
In any case, it is crucial to see that that 'middle 75%' will rally to the cause of the oppressed or to the outrage of social corruption (and prisons are part of that social corruption) far more vigorously than they will rally to their own directly stated "interests."
And of course this is another reason for a left in action to ignore the tears of those who want it to have "demands" that stem from abstract policy analysis rather than on what enrages people.
Carrol