I think that the main problem is not unscrupulous or cruel leaders. The main problem is that many people don't in actuality care about non-partisan fairness toward other human beings. That is what makes it easy to sell entire nations on the idea of "getting those bad guys."
And it doesn't matter who the bad guy of the day is. Okay, it matters greatly to the recipient of cruelty, but not in principle. People find excuses for the injustices regardless of their level of education. Educated minds find fancier excuses, that is all.