Since originally posting this question, I've done more reading on "domestic servants," both in the USA and UK. Far from being the exception, it seems like having servants was the rule. A number of sites say that for any but the poorest households to function, they needed at least one maid (called "a maid of all work") to help the woman of the house with duties from taking care of the children to food preparation. Many families had what would appear as reciprocal relationships with neighbors where their children were placed and worked for someone known to the family.
Here are some links for further information:
Domestic Service, the forgotten occupation [http://www.victorianweb.org/history/work/burnett3.html ] says that, "Throughout the nineteenth century and until the First World War domestic service constituted the largest single employment for English women, and the second-largest employment for all English people, male and female. Yet it is a largely unknown occupation."
Antebellum Cincinnati Domestic Servants [http://curiosity.cs.xu.edu/blogs/antebellumcincinnati/topics/domestic-servants/] tells how, before large scale immigration, " many households would basically borrow children from neighboring households. If a family didn’t have any female children of their own they would take in young females from neighboring households who would help take care of the home. (309) When immigrants began coming to America in large waves they filled the void and domestic servants became popular in rich and middle class households."
Maids in America: the decline of domestic help [http://www.theatlantic.com/business/archive/2015/09/decline-domestic-help-maid/406798/] begins "For centuries, a woman’s social status was clear-cut: either she had a maid or she was one. Servants—often live-ins—who did the bulk of the cooking, laundry, and childcare were an indispensable part of life for virtually everyone who wasn’t a domestic worker him or herself."
Domestic Servants – Part 1 – Women [https://lifetakeslemons.wordpress.com/2010/02/16/domestic-servants-part-1-women/] says "Their number was a symbol of social standing with the aristocracy employing as many as fifty while those of the middle class might employ three or four, or as was often the case, only one, most likely a maid of all work. . .. To launder, sew, empty chamber pots, dust, haul water for baths, light fires, and shop–all these duties fell within the realm of women’s work."
Tomorrow: Living Life as a 19th Century Servant [http://www.fourpoundsflour.com/tomorrow-living-life-as-a-19th-century-servant/] says that "In England and America in the 19th century, housework was incredibly laborious. If you could afford it, you got a servant."
The Rights, Duties, and Relations of Domestic Servants, Their Masters [https://books.google.com/books?id=I7gDAAAAQAAJ&pg=PA1&lpg=PA1&dq=%22domestic+servants%22&source=bl&ots=u7_wk1JY7H&sig=GcRzbfeG3sMXU6i8M_4uI7tmD7s&hl=en&sa=X&ved=0ahUKEwilvoGJgMLQAhUl1oMKHXBIB7E4ChDoAQhfMAc#v=onepage&q=%22domestic%20servants%22&f=false] begins by saying " is an e-book that details rules for hiring, taking care of, and firing domestics. Workers were paid quarterly, and if the quality of their work was in question, there were rules favoring the employer which made partial or non-payment of domestics possible.
"The Biddies" -- Irish Domestic Servants in Early America [https://www.americanhistoryusa.com/biddy-irish-domestic-servants-in-early-america/] tells how "These women cooked meals, cleaned house, cared for the children, made the beds, and other tasks of that nature. Many of them came as indentured servants . . . -- meaning that they worked for room and board to pay for their passage to the United States. After a no-frills journey, they would begin a labor term of four to seven years. During this period they were treated the same as slaves -- they could be tracked down by bounty hunters if they fled. . . . Until mid-century, debtor's prisons were common and anyone deemed not to fulfill their end of the agreement could be thrown into one. Women were also vulnerable to sexual assault, since they had almost no legal recourse to pursue claims."
