The simplest explanation for why Harry Kim never got promoted is because the Voyager was a self-contained crew isolated in deep space and there wouldn’t be any opportunities for upward mobility unless some higher-ranking officer retired or died.
It’s like asking why Gilligan never got promoted.
And yet Tom Paris got a promotion… And let’s not forget that she got him out of prison to be their pilot…
Then a demotion, followed by another promotion, if I’m remembering correctly
Frankly a bit problematic given that Janeway and Paris made a bunch of space salamander babies together… doesn’t Starfleet have guidelines about unilaterally promoting someone you had that kind of relationship with?
Absolutely!
Do you think they ever reported that? 
Probably buried in the fine print of her official report along with the “Tuvix” incident.
What happens in the Delta Quadrant, stays in the Delta Quadrant!
That bit made me laugh so much
I wonder which would be more awkward; Janeway giving birth to a litter of hyperevolved space salamanders conceived with a subordinate or giving birth to a half-holographic baby?
That did happen with some measure of regularity on the show. Maybe not retirement, but they definitely lost a few crew members over 7 season.
True, but few were officers who outranked Harry. I think most were enlisted personnel.
https://home.strw.leidenuniv.nl/~jansen/st/voyager/casualties
Apparently Janeway had an unusually high number of spare crew members on hand just like the shuttles and photon torpedoes.
Even (and especially) if the crew shrunk in size, all the same menial tasks would still need to get done, so promoting people wouldn’t really help anything except for making a top-heavy bureaucracy with an ever-smaller number of workers being commanded by a larger number of officers. Most of the people who died were redshirts (or equivalent) and not the bridge crew.
I liked that they actually addressed this entrenched social inequity in the Battlestar Galactica reboot. It’s one thing to accept that you’re stuck in a lower-status job for the duration of a mission, it’s another thing entirely to realize you might not have any opportunity for advancement for the rest of your life.
At least Harry was a commissioned officer who got to work with the bridge crew. Some other poor bastard probably spent seven years cleaning the space toilets.
There was an exchange on Lower Decks between captain Freeman and her first officer talking about how the menial tasks weren’t working to break the spirit of ensign Mariner:
Ransom: I’ve got her cleaning the [bleep] out of the holodeck’s [bleep] filter!
Freeman: [somewhat shocked] … people really use it for that?
Ransom: Oh yeah. It’s mostly for that.
had to get rid of marquis somehow…
https://screenrant.com/nicolas-cage-star-trek-movie-love-enterprise-hopes/
Listen, Nick, If you get that call, whatever they offer you, your answer has to be clear.
