Hmm, I see what they are saying. I think it's the most true in places (like the USA, where the articles author is from) where a lot of people rely on underpaid immigrant nannies.
People often mention on here about how it's amazing that women go back to work after birth so soon in the USA. Yes, but they rely on underpaid exploited workers to do this.
On the other hand, if the childcare worker is paid a fair wage and has fair working conditions, it's not really "at their expense" is it. That is making the sexist assumption that domestic type work like childcare can't be a fulfilling and successful career. And that definitely isn't true - it can be.
After all, that isn't an assumption made for other things. If I pay an accountant to do my tax, I'm not considered to be exploiting him or her, even though I could do it myself but am choosing not to.
Whether we, in this country, fall in to the first category or the second, when it comes to childcare workers wages and conditions is the question.