The slaves, don't act like..well slaves. They seem to have no problems with being ripped from their old lives and forced (or at least strongly encouraged) to serve others. Moments after being captured and forced into slavery they are allowed to escort potentially vulnerable children around with no one keeping any eye on them. The masters seem to have very little control of their slaves who seem to (mostly) love them unconditionally. Then there is the fact the lesbianism is seen as the norm.
Have you... read the commentary? It can be found beneath every strip, and addresses some, if perhaps, not all of the concerns expressed here. Quite a few of which can be chalked up to the culture being portrayed.