Your principles are admirable, but might only make a change in the very long game. If one takes a job with a household employee(s) perquisite, then someone like you can make an immediate, actionable change in someone's life right now. And you have the opportunity to extend that change into their family.
Much of success is embodied in modeled behaviors and attitudes. By dint of employing them, you have the opportunity to model for them success-oriented attributes, and let them pick and choose what is culturally and socioeconomically prudent to adopt into their lives. If you want to go a more activist route, if you and they have children you can intertwine their lives together and sponsor (tuition, fees, clothing and supplies) their children (if they are young enough) to the international school and after-school activities that expatriates usually use, and give your children a cultural exchange education second-to-none in the process. The possibilities to make positive change are endless, and only limited by your resources. Just be careful of fostering dependencies, and be open with those who you partner with in the endeavor about the probability of you getting assigned out of your host nation and abruptly changing their situation.
By contrast, advocating against "facilitating apartheid with a brown face", through various political means at your disposal as an individual citizen in the developed world, helps to eventually effect change through policy circles, but usually only at a very long game timeframe. Typically in the years to decades scale.
We need BOTH kinds of advocacy to effect humanitarian change. But if you are already in a position to make a personal, first-person, actionable, on-the-ground change, I urge you to grab it with both hands; there are too few people in this world with your principles, perception, and opportunity. Whether you are facilitating apartheid or making positive change depends upon the deep nature of your interaction, not the overall first-blush official description of the relationships.
Very rarely is this kind of change a binary switch, and it almost always involves a "getting from Point A to Point B" transition that has the trappings of distasteful practices, but the on-the-ground reality for most individuals (even highly privileged ones like most of us on HN) is resources are limited, and we have to get creative with how we re-purpose (and overload, to borrow OO lingo) normal, everyday interactions with positive change payloads.