Sometimes, morals don't travel well. Often, what is appropriate to one culture or time period is repugnant to another. Thus, when dealing with other cultures, an author must make a choice. Some attach the attitudes of their country to the people in the story, resulting in a potentially anachronistic but enjoyable read. Some, however, research the culture and make an effort to reproduce the attitudes of the time and place accurately, even when they are wildly different to what the author might consider sensible. Thus, one ends up with a deliberate case of Values Dissonance.