America assumes that she's just getting three temporary maids when she meets Anne, Mary, and Lucy, but they turn out to be something far more valuable: three new BFFs.
Typically, maids are meant to be seen, not heard, and spend twenty-four hours a day under the command of the Selected to whom they are assigned. Being a classic class warrior, however, America has little interest in this arrangement and approaches these ladies instead as equals. The results are amazing. Just look at this scene from early on in her stay:
Listening to them and joining in when I had something worth saying, I couldn't imagine anything more entertaining downstairs and was glad to have such company. (14.9)
Even though she's higher on the totem pole than her new friends, America finds them down-to-earth and relatable—something that can't be said about most girls in the Selection.
There's plenty of darkness hiding in the background, however. Most notably, we learn from Anne that none of the girls really has a choice in working at the palace: "Some of us were born here. Mary was born in the castle, and her parents are still here. I was an orphan, taken in because the palace needed staff. [...] Lucy was sold to the palace" (13.159).
Yes, you read that right—Lucy was sold to the palace. Her family took out a loan for medical treatment for her mother, but when it didn't work and they were unable to pay it back, they became indentured servants for a wealthy family. Lucy started a romance with the family's son but was sold to the palace after the matriarch of the wealthy family found out and was horrified.
These stories make America even more sympathetic toward her maids' plight, which is why she's so insistent that they come to the royal family's safe room during the rebel attack, despite the fact that this is against the rules. She'd never be able to live with herself if something happened to them—her friends—while she sat around safe and sound. It's both a testament to America's fundamentally good nature and a scathing critique of the imbalanced power structure of Illéa.