The non-niscient narrator in Rivka Galchen's story

Impressed w/ Rivka Galchen's story in current NYer, Can I Help You?, one of the rare stories to use the non-niscient narrator as a device: that's a narrator who's the opposite of omniscient but in fact knows significantly less than the reader does. The narrator here is a young woman who works as a supervisor in some type of call center - seems to be that the "resolve" disputes between the people and their medical-insurance companies. The narrator describes a difficult worker with bad spending habits, at least in the narrator's opinion. Only gradually do we learn that the profligate employee is the narrator's sister, and there's a whole history of family jealousy and dysfunction behind them. The more the narrator tells us about how she is trying to help her sister, the more we learn and understand about the narrator's callousness and, incidentally, about the horrors of working in this kind of modern-day sweat shop - a job that the narrator is perversely proud of: she likes to think that they're "helping people," one of the prime sources of happiness and satisfaction in life, but we can see around the edges of the narrator's knowledge that her company is paid essentially to move complaints along w/out resolution: this seems to be a story of two pretty much ordinary young women trapped in a George Saunders corporate dystopian world.