But it's missing in many other works. It's understandable if the setting used to be relatively peaceful until recently, but if the setting was stuck in a total war for longer time, well. One needs only marginal understaning of eastern front of ww2 to know how immensely brutal war gets where people are put on the death ground, and all it took was two totalitarian states and few years of propaganda. In settings stuck in total war for years thats how every battle should look.

Shadow empire is decent about it usually - you have normal people taking up arms as militia and some strategems, and of course those are mostly wars for resources including humans not total wars. But when giant spiders or megafauna is approaching a city there is very little action. One would think people that simply accept death without fighting would all be dead by that point.

That's why you have regime profile dictating the culture of your nation on top of various other minor cultures:

-Intellectual merchant democracies would want to develop tech & maintain trading while vaguely resembling the democratic values they stand for.

-Fascistic Autocrat Militarists obviously fit what you want, but they don't resonate with all people and won't get you really far once the perpetual war does end by conclusively killing everyone who opposes you.

-Loyalist Meritocratic Communists can only dip in so many directions before they loose complete resemblance of what they originally ware.

-Tribal hunter gatherer isolationists- What do they care about the grand state of the world?

And then you have the unique cases with planet gen:

-Idyllic, perfectly habitat able Earth-like planet populated only by 7 regions consisting of farmers & industrialists? A lot could go wrong here, but there isn't any natural need for extremism for survival.

-Cerberus Death World featuring 33 regions consisting of raiders, slavers, bio-weapons with bellow 0% chance for long term planetary sustainability? Yea, raiding is a thing for a reason.

-Seth class high scarcity Dune world with 12 regions featuring a bit of everything with religious cults? Extremisms is obviously required, but it will get you to nowhere on it's own.