Many people don't know how to say I'm sorry, because they grew up in an environment where "I'm sorry" has no meaning whatsoever. Because they grew up in an environment where that feeling is nothing, making that of our way of acting something everyday, where that word has no value, no meaning.
They believe then that they are the holders of reason and in that sense they will try to impose their own ideas and actions regardless of who they affect with their actions.
In that sense, these people do not have the emotional resources to offer an apology, much less the mercy in their hearts to acknowledge their mistakes and find ways to compensate for the harm they have caused