Are female officers addressed as "sir" out of writer ignorance, or some intentional reason?

A lot of movies and TV shows that you see that in are futuristic and sci-fi movies. Part of the purpose is to just grab your attention like it does, but the other purpose is to show how they are different from our modern military.

In essence, they are saying that they have moved beyond gender bias to the point that every officer is just referred to as "Sir."

Probably the best recent example is the remake of Battlestar Galactica series.

Some fictional settings assume that in the future such distinctions would be dropped in favor of a consistent honorific. I doubt this will ever be the case. But changes always happen, so maybe in a few decades that young female Ranger LT will be called "Sir" by her troops.

Refer to this question from English Stack Exchange: Can sir be used to address female officers. In the American military, you would never address a female officer as "Sir."

In the United States, you would address the officer as "Ma'am" and not "Sir". It's considered disrespectful to use the term "Sir" for a female in both the army/navy and outside.

The only place I've ever heard female officers called "Sir" is in futuristic fiction, e.g. Star Trek. But even there it's not universal. Apparently even some fictional female officers dislike being called "Sir." According to this Trekkie page she was primarily called "Captain" but by protocol she was supposed to be called "Sir."

In the American TV series Castle, all of the detectives (both male and female) address Captain Victoria Gates as "Sir."

With reference to the mere mention of Star Trek in your question; I'm going to answer this with credit to the answer of the Sci-Fi SE answer to this question:

What's the origin of referring to female superior officers as "sir"?

With credit to Praxis(Sci-Fi SE user), this is their answer with a score of 19:

Professor De Witt Douglas Kilgore, a specialist in English literature and cultural representation at Indiana University, has done significant research on race, gender, and equality in speculative fiction. In his book Astrofuturism: Science, Race, and Visions of Utopia in Space (2010), he attributes calling females "sir" to Star Trek :

The Star Trek franchise reinforced this idea by the convention of awarding its female officers the honorific "sir". This innovation was established in the second Star Trek film, Star Trek II: The Wrath of Khan, dir. Nicholas Meyer, Paramount, 1982.

Likely, Kilgore is actually making reference to the use of "Mister Saavik" in the film, and perhaps equating it to "sir". At the very least, as "mister" is a male title, it foreshadows the use of "sir" in later Star Trek works. In any case, Kilgore's research suggests that we owe the use of "sir" as a bi-gender honorific to Star Trek, whether it first occurred in The Wrath of Khan or a few years later in TNG, at least as far as science fiction is concerned.