I’ve watched some vintage US detective dramas recently. All enjoyable (such as Kojak), but a curious soul like me has questions.

I know the rank structure can vary from city to city (e.g. detectives being called inspectors in San Francisco), but I sort of understand the structure with most city forces, such as, in ascending order, officer, sergeant, lieutenant, captain, etc. I know how they may equate to UK police ranks.

But in some US dramas, there are captains who are always in plain clothes and exclusively instructing/leading detectives.

Can captain be a detective rank? Could a precinct have two captains, a uniformed one and a detective?

Happens in the UK, too and was illustrated in The Thin Blue Line, where Rowan Atkinson plays Inspector Fowler, head of the uniform division of Gasforth Police Station; and, David Haig, as Detective Inspector Grimm, head of CID.
Depending on the era of tv police you are watching, most of it will be based, loosely on the LAPD structure, since most of the writers are in Hollywood, though they were rarely heavily researched. Police Story, was produced by Joseph Wambaugh, a former police officer and tended to be a bit more accurate in its details, compared to Aaron Spelling's shows, like The Rookies, Police Woman or SWAT. Jack Webb's Mark Seven shows (Dragnet, Emergency, Adam-12) were often based on actual cases and had a lot of involvement from police and emergency services. Others kind of fell somewhere in the middle, depending on the writing staff and show runner.

I have always heard Barney Miller cited by actual cops as one of the more accurate depictions of the average police precinct, rather than the big dramas, like a Kojak or Hawaii 5-0.

Nothing beats Police Squad, though....

Yeah, but we had Huggy Bear....

They just meant his cologne; Hulk got kind of musky.

It's a great series, all the way through (even in the final, shakier, couple of series).  My local PBS station used to run it week night and I used to tape it and rewatch it.  Later, I sprung for the DVDs and discovered I hadn't seen it all, as there were a couple of episodes that were not shown, because of blackface comedy in them (homophobic was okay, though, and other national stereotypes).  Even when it isn't necessarily thoughtful about the object of jokes, it isn't really mean spirited and the characters are great, even if they don't necessarily evolve.  It is a pretty good look at life in retail, even if it was done in a different era.

The best parts of it, though, are character-generated.  Yes, they get some great customer interactions and memorable guest characters; but, at the heart, it is the main cast and you even start anticipating the jokes, after you get to know them.  It is really evident in later series, as the audience is often laughing before the punchline, as they can anticipate what is coming.  I've probably watched the whole series a dozen times and it is still funny, with that familiarity.

The sequel series, Grace & Favor (shown as Are You Being Served Again?, in the US) was pretty good, too.  The premise of them living on a country estate and acting as the staff to run the hotel business that earns them their retirement money, is a bit thin; but, it is mainly an excuse to have them all back together, doing their thing.  It does throw a few interesting curve balls, like Miss Brahms being the object of affection from a female magistrate, Mr Humphreys being a similar object of desire by a new character, Mavis, the cook and daughter of the farm manager, and Mrs Slocombe being the same for Mr Moulterd, Mavis' father, who knew Mrs Slocombe when she was a Land Girl, during the War.  Add to that, there is an episode where Mrs Slocombe's missing husband turns up, as a prospective buyer of the estate and they must disguise Mrs Slocombe, so that he doesn't learn that she isn't living at his standard.

There is a click-bait video on Youtube, which claims that the entire cast is dead, now; but, that isn't correct.  The principal cast for the bulk of the series is gone; but, Mike Berry, who played young Mr Spooner, in the later series (replacing Trevor Bannister, as Mr Lucas), is still going, as is Doremy Vernon, who played the Canteen Manageress; Penny Irving, who played Miss Bakewell, Mr Grace's secretary; and, Vivienne Johnson, who played Mr Grace's nurse.

There is also a movie version, from the 70s, back when there were several theatrical films based on popular tv series (Rising Damp, Callan, The Sweeney, and some others).  It is mostly a retread of gags, in the early part; but, does take the staff on their holiday, to Spain, which was the end result of one of the tv episodes' plot.  That includes some decent hijinks; but, the timing doesn't work as well, without the live audience.  I suspect it worked better in the stage version.

Decided to treat myself to a month of Night Flight Plus. Really liked the show from what I've seen and I think it's great that they've got a live stream of the show if you're not in the mood for wading through the extensive video library. Kind of wish other streaming sites did this