You're mixing concepts. In my original post I talked about how Roman slaves considered wifely chores beneath them. Not all slavery systems were built equally. Their slaves were just workers that weren't citizens so they didn't get the full set of rights, but they were paid and could buy their citizenship. I think it's rather disingenuous to compare that to rape.
With or with out Roots, slavery has been a moral abomination with no justification in the west since the Enlightenment, and certainly since the American Revolution. And as modern economic systems and industrialization have progressed since the mid- 18th century, slavery even lost its comparative economic advantage. Yes, a select few in the American south made handsome sums from slavery up to the time of the Civil War, but the impact of slavery was devastating to the southern economy and people as a whole. It took them nearly a century to overcome the gap in competitiveness that slavery created.
Modern economic systems have certainly pushed slavery towards the historical trash heap, we finally have a solid system that works well without that ownership idea. Until capitalism had the kinks worked out though slavery was just as valid as anything else out there. I think you're overly hung up on your moral interpretation of the situation. According to Marx the worker is always a slave regardless of his label and the activities of the owner are always immoral. We all know that's BS. What I'm questioning here is at what point does the relationship truly become immoral. And I don't think that point has any relationship with the word "slave".
I really think you need to do some serious contemplation on what it means to be a slave. You seem to be trivializing life spent without freedom, or perhaps trivializing the blessing of freedom itself.
In Mexico right now there are women working 12 hours a day in shoe factories and making $2 for it. If they take more than 3 bathroom breaks in a day they will be fired. At times they are locked in (the factory bosses get in trouble for this when they're caught) and cannot leave for any reason. On days when they aren't locked in they will be fired for leaving. Now according to the definitions we have they are employees not slaves and therefore this situation is morally acceptable. Clearly this is not a morally acceptable situation. Therefore what makes someone's labor circumstance morally reprehensible is not tied to whether their labor falls under the term "slavery" but something else. Something that's a little harder to define. Something that has historically existed under slavery, but slavery has existed without it. And something that has existed historically under other worker-boss relationships, but has never been garaunteed to exist under any individual system.
There is a logical falacy there. Just because a practice is not slavery does not make it by definition morally acceptable.
As to the Roman slave system, perhaps you know more about it than I. I did not understand it to be all that egalitarian. There was a major slave uprising in the first century BC that nearly toppled Rome. Tens of thousands were killed and all of the captured slaves crucified. It sounds to me like they did not especially enjoy their condition.