The starting point here is that what the writers offer to us (behind the scenes, without ever quite managing to put it on screen) isn't plausible. What the costuming department offers us might be more plausible, though. Anything would be an improvement, after all. Lemonade out of rotten plums, and all that.
But then
you threw out whatever the costuming did in the original Trek movies because Valeris just happened to have a costuming error. You're throwing out all original intentions and taking 1 costuming error and then making your "own" conclusions, declaring it as fact, to debunk what I initially said. You, dear sir, are moving the goal post.
The original intentions of the movies stand, they were cadet uniforms.
They were intended to be cadet uniforms.
They were used as cadet uniforms.
But since you want to try and over analyze a costuming error, the difference between Valeris' uniform and Saavik's uniform go beyond the shirt. If you know about the costuming notes for these uniforms,
the red strip designates cadet. Valeris
lacked this. Saavik was a cadet.
Moving on,
If tidbits from the Trek universe aren't allowed, then tidbits from yet another, even less related universe (ours) are certainly banned. West Point doesn't exist, there is no USN, and nobody ever wrote those helpful wikipedia articles on how the US military works.
You, again dear sir, made the first strike and tried to out rule my real world examples. If you were to weight the two in this conversation, anything post Trek would be useless as it has been completely wiped away with this movie. What would have, could have, should have happened
no longer applies while my real world examples, no matter how much you cry and holler,
can apply.
Why?
Star Trek has always been modeled after the US Navy, especially in the Trek movies you keep referencing to. So why wouldn't that example not apply if its the main institution that ST has developed its ranks and system off of? Really.
But besides that, whatever you think still doesn't
represent what's on screen. You keep making wild speculations instead of accepting the fact that it was the intent. You don't want to acknowledge the system of midshipman ranks or how it is impossible for a cadet to be commissioned at the same time because you want to over analyze and come up with these wild, so far left field I don't even know where you get these, ideas.
Star Trek is not rocket science. It's not some strange creature you got to dissect. It's a god damn science-fiction show/movie written by people who probably couldn't give a flying fuck as long as it's believable enough to work. If you have to spend your time trying to figure out the reason every. single. thing. in the movie then you're just defeating the purpose of mindless entertainment and taking it too damn seriously.