Recently, a friend's offhand remark about sci-fi authors lacking imagination in how they name fictional wars prompted me to reply that it shows they don't know what their imagined space-faring civilizations are fighting over, and that in turn betrays an ignorance of real-world history.
In turn, this exchange reminded me of a webcomic I'm reading, which shall remain unnamed. It's a good story that snuck up on me page by page. It also makes a good case study for this exact problem.
The premise is classic: in the future, humanity fights a war in space against meanie aliens. My problem with that is how, because right from the start it turns out lone ships from each side will meet randomly in deep space and just sort of have at it over... what? Down the road it turns out said aliens practice slavery, so if nothing else they'd have an interest in capturing the human crew. But as any fighter will tell you, fifty-fifty odds are terrible. Even if you win, you'll get hurt in the process, often badly. Possibly so much as to make your victory moot.
The problem is compounded if your goal is to take people into slavery, because slavers always have to expend a lot of resources just to keep their victims under control. It's incredibly inefficient. Many insist it must make economic sense, otherwise why would people do it? To which I always tell them: because they want to. Humans are obsessed with controlling everyone and everything around them. And that hasn't changed even as we progressed from oar-propelled ships to steam engines, then jet engines, and all the way to same-day delivery.
Sure enough, the aliens in this story have cultural and historical reasons to do what they do. However it comes back to bite them so often, any reasonable person would just find better ways of dealing with problems.
It makes sense that ships in a galactic war would be so thinly spread as to find themselves alone most of the time. Star Trek didn't pull that out of a hat: it used to happen often enough early in WW2. And yes, sometimes ships would fight just because it's sort of what you're supposed to do when meeting the enemy. I'm still left with the feeling that often writers get these details right accidentally, not because they actually read about it. Let alone from personal experience, like Gene Roddenberry did all those years ago.
"Write what you know" is bad advice. But you definitely have to know what you write. Imagination without knowledge is a castle built on shifting sands.