Do they also teach about Comanche slave raids and other intra-native wars, and the native American treatment of prisoners of war and slaves, putting European conquerors in context as just another warring 'tribe', just a more successful one? Or do they teach a one-sided morality play version of history?
What history course would you expect to see this in? Courses don't tend to contain "by-the-ways" for things outside of the course material. Should it be against the rules to have a course specifically on the african slave trade? If somebody is teaching a course on the italian renaissance, should they be obligated to mention that great art was made in china too?
College history courses aren't "one-sided morality plays."