I think what these agents are advising, and definitely their advise is heeded, amounts to slavery. It doesn't have to be this way. We pay our maid more than double the minimum suggested. She gets a day off. When she has finished her work, she can go out and meet her friends. This is just normal and humane. I heard someone say the other day that maids don't "run away" , we are not talking about children here - they may "choose to leave" because the conditions they are in, or their treatment, is unacceptable.
There are those here (it's fair to say, generally, Arab) that consider our approach as being bad for "the market" in maids - pushing up the salaries and making maids "run away" when they realise they can earn more elsewhere. It can be argued that even the minimum salaries offered are significantly more than they could earn in their own countries, but for me their treatment is more important than the salary itself. Personally I would feel guilty at paying only the minimum, but that is from my western expat cultural perspective. For most western expats here, we have maids not because we can't possibly do without one (we managed perfectly well at home without!), but simply because it is an affordable convenience.
So - if you have a maid, do the right thing!