Hiring an Immigrant as a Nanny

From personal observation, and viewing some family members, it seems that many immigrants, legal or not, are often hired as nannies. When I'm at work, I constantly see women of other ethnicities taking care of (generalizing) white/typical American children. It's easy to tell a nanny apart from them being the mothers, and many of them typically speak their native language whilst hustling around the children.
My aunt, who received her official naturalization document to be a U.S. citizen, takes care of a young boy as well as another child. I also take notice that most of the time I go out, especially in San Francisco, I typically tend to see many more nannies than parents with kids. I actually addressed this to my mom, since I was curious as it is also typical to see in the media, and she told me that it was good money. Albeit there are negative outcomes sometimes to the child who is constantly with the nanny more than the mother, that's not the case of this post. 
I decided to do a quick google search, typing in "hiring immigrants as nanny" which turned into "hiring illegal immigrants as nanny" and I was surprised that none of the links were news articles. There are so many articles about "nanny taxes," why or why not parents should hire illegal immigrants, and it surprised me how many results I got. The very first link is 'Risks to hiring an Undocumented Nanny.' What angered me a bit, under their risks was that "If arrested while at your home, your children could be left there, alone. " Yes the child is important, but it makes it seem like the child is the only important aspect, not the immigrant who probably has their own family and children to take care for. 


Sources:
http://www.nolo.com/legal-encyclopedia/risks-hiring-undocumented-nanny.html