O'Brien is a "chief," Jonas and Cutler hold the rank of "Crewman," and I think those are the only enlisted personnel who have lines and appear in more than one episode. Starfleet seems ridiculously officer heavy.
Is the enlisted/officer distinction different in Starfleet from traditional armed forces? And where are all the warrant officers?
I saw a video once that said, for the size of the Enterprise ships, the onboard populations are actually really small. Presumably the various departments and quarters are distributed throughout the ship and it’s just very sparsely populated. Doesn’t make much logistic sense to me, but if they had everyone centrally located with the usual crew size, much of the ship would have been empty.
Roddenberry gave conflicting direction on this. By the time TNG rolled out, his position was that most of the crew were officers.
But it was a long and confusing evolution. After intervention by the network after the TOS pilot, turned Janice Rand’s yeoman role, which is one of the most senior NCO roles on a naval ship, into what seemed to be a personal secretary. NBC was no more ready for a senior NCO who was a woman than they had been to have a female first officer Number One.
Discovery makes things murkier by mixing in ‘Chiefs’ as a title for department heads but never actually saying who is chief medical officer or chief engineer.
Lower Decks seems to have ensigns being hazed with junior enlisted tasks. However, Prodigy has introduced warrant officers as another career pathway outside the Academy.
Janice Rand’s yeoman role, which is one of the most senior NCO roles on a naval ship, into what seemed to be a personal secretary.
A yeoman is a person who does administrative and clerical work in the modern Navy. They run the gamut from E-4 to E-9. That's low enlisted rank to the highest. Rand could be an E-9 Master Chief Petty Officer Yeoman for all we know. That would make her the appropriate rank to be the captain's administrative assistant.
Just to say the way the role is presented kn television doesn’t highlight the sensitive roles such as being the senior NCO responsible for oversight of enlisted personnel performance evaluations or communications with command.
It would be very senior AO role on a capital ship, but she mainly comes by to get the captain to sign stuff.
Strictly speaking, O'Brien is a "Senior Chief Petty Officer" in rank, and a "transporter chief" in role. Those two happen to both include the word "chief", but they're no more related than "Lieutenant Commander" and "chief engineering officer" are for La Forge. I believe "chief", on its own, is referring to any of the ranks of NCO with chief in the title, [master | senior] chief petty officer.
Starfleet seems ridiculously officer heavy
Indeed it does. Whether this is actually true, or just an artifact of the fact that we tend to primarily watch the actions of those in command, I'm not sure. But if it is the in-universe reality, that's probably a consequence of the post-scarcity society and the abundance of time and education people have in order to become officers.
And where are all the warrant officers?
I'm gonna be honest, I've tried numerous times, but have never managed to really understand what WOs are. I have this vague sense that their rank sits somewhere between that of NCOs and of commissioned officers, and that they're involved in more unusual or specialised tasks, but I don't think they normally sit in a regular chain of command, and I'm not really sure how it works.
It's hard to show the intricate workings of hundreds of crewmen. It's just not practical or in the budget. Crewmen pop up every now and then if you pay attention.
Someone said Master and Commander can be seen as similar to Star Trek, and it certainly has the same ship command structure. The crewmen play a larger role and they really cover the dynamic. Very much worth a watch with or without connection to Star Trek.