Artificially inflated wages are one thing, but seeking out a qualified moderately educated nanny and paying her as little as possible simply because she is in the unfortunate position to have to accept anything at that point in time is wrong.
Are you objecting to minimum wage or to rates of $10-$15 an hour? You can not claim with any credibility that 25%-100% more than minimum wage is not a living wage or that charitable pay is warranted in this situation. There are many positions that do not pay 50K a year and which require a full degree not just moderate education. A nanny is no better than the employees who chose to work in those jobs/professions.
When your argument rests on your ability to denigrate workers in a particular field or those with less education than yourself, you lose the righteous ground. This is not about being "better" or "worse" and the fact that you make it so speaks volumes about your own character.