Poor is relative, just because it doesn't seem like much money to YOU, it doesn't mean it isn't a good wage to them and obviously it is or they wouldn't leave their families and friends to move here would they? Comparing it to Slavery is almost an insult to them, I'm pretty sure they wouldn't think of themselves as slaves......
The whole topic of abuse is something different altogether but your original question is more in reference to the wage not the working conditions and when you consider they SHOULD get free boarding, food, flights home etc it isn't bad compared to your 'average' local like Skyhook mentioned.
Well maybe you should get a maid and pay her 8k then if you are so generous, put your money where your mouth is ! OR don't get a maid at all and do what most do - raise your own kids and clean your own toilet !
FYI - I don't have a maid and can't imagine ever having one, the idea of a FT stranger in my house puts me off alone.