For Carver, this narrator’s point of view coincides with the Millers’ because both are peering into someone else’s life. Meaning, the Millers are peering into the Stone’s life and speaker is peering into the Millers’ life. The story was written this way for that precise reason- the writer, through our narrator, wanted us to feel as though we were being voyeuristic just as the Millers are. Thematically, if we chose to read what the narrator is giving us about the Millers, we are no better than the Millers snooping around on the Stones. Our keys to the Millers’ apartment are the words given to us by the speaker; the Millers’ apartment is the book in which we find those words where we can come and go as we please.
Going back to the original definition of an “Omniscient Narrator,” some might argue that the narrator in this story does not “report all.” I would disagree. I say this because of the story’s over-all simplicity in that it only provides us with the bare minimum of details about things such as the setting. If the speaker ended-up “reporting all” or giving us more than what he did (things like specifics on what Bill and Arlene were thinking when the other spent more time than expected on their trips to the Stones’ apartment) the since of starkness and straight forwardness would have been lost in the details.