There's those countries and regimes that accept their history, including all the terrible stuff, and those that try to hide or deny it.

Among other things, trying to hide it speaks of terrible insecurity. Your people don't love you any more if they find out? What about instead, you work on being such a good government that people love you even as they know, because you're so working hard that bad stuff will never happen again?

#tiananmen but also certain places in US