Why Trollope's narration is different from the "omniiscient" narrator

Sorry to perseverate (?) on this topic but Trollope's Barchester Towers just seems to continually raise questions and pose problems regarding the "omniscient" narrator. There's a dichotomy here: Trollope's 3rd-person narrator is indeed omniscient, not only knows all the facts of the story but obtrudes at times w/ his own voice, offering commentary on the story and at one point giving away - stating well in advance of the narration, that is - some key plot developments (Eleanor will never marry Slope, Dear Reader...). So the omniscient narrator is not some all-pervasive and immaterial narrative God - the narrator is much less than a God, in fact less than a first-person narrator who is really just a character in the story give voice - but the Trollope narrator is - Trollope. It makes sense that the author-as-narrator would arise in Victorian fiction, 2nd half of 19th century, which - a JH Miller wrote in his famous critique - was the epoch of the disappearance of God - replaced by science, business, the humanities. In a Godless age, the novel creates the godlike narrator in his own image, so to speak. By chance, an interesting piece in current NYTRB on narrators and narration - describing a reading at which a young person in the audience found the very idea of an ominscient narrator "spooky" (was referencing a novel, Everything I Never Told You, in which the narrator is reflecting back on past events - he or she knows all the details and the events were long ago). That's not surprising as literature now is dominated by first-person narration or the old-fashioned omniscient narrator who "disappears" in the work (the author of the NYT essay rightly summons Flaubert on this point: the narrator must be everywhere and nowhere - to me, that is the ideal of fiction), but there are few Trollope-like narrator as author books appearing recently - the author of the essay recalls Fates and Furies, for ex., in which the author speaks to us occasionally in brackets, the text separated from her narration. It's not exactly that Trollope's narrator is omniscient - it's that his narrator knows everything the author (Trollope) knows, but no more.