In a highly advanced Sci-fi setting, yet human combatants and manned vehicles are still dominant in wars -- Why would that be?
Imagine the world being highly advanced in technology, even FTL capable space civilization. The assumption is the logical progression would be that most of the combatants will be replaced by drones, unmanned battleships, autonomous space torpedos etc, maybe even the warfare being totally autonomous with some prompt to the AI, considering the AI technology must be highly advanced as well. They are just too cost-effective and combat effective like IRL and lethal threat against traditional armies. For non government armed groups like pirates they are also extremely effective.
Yet in this world the "military personnel" does not equals to drone controllers at all. There are still human infantries, pilots and ship crews on the first line of combat, although highly advanced drones and AIs exist they are more of a supportive role in the military. So just like a "normal" sci-fi story that you have foot soldiers, pilots or ship commanders as the heroes instead of making them all being drone/autonomous missile controllers. There can be mass produced drone armies but they dont replace the human armies entirely.
How or why would this be the case? I find the most common answer would be "AI rebellion caused everyone to limit them", but that limitation would be too generic and intentional. There are other settings like "populations/slaves are too many so human lives are more expendable than drones" but it would be too over the top if the civilizations in the setting are still "normal" societies that value the lives of their population to a degree (and of course dont have slaves).
This can also be expanded to other occupations outside warfare i.e. artists/journalists/programmers etc still do their jobs without generative AIs, even tho AI being highly advanced in the settings. Simply saying "because law limits AI" seems to be not persuasive enough.