Underrail is one of the more reactive cRPGs you can possibly play. As an example, the first quest you have in the game involves you clearing out and re manning abandoned outposts outside SGS for various practical reasons. You can half-ass it and only turn on the bare minimum, or turn all of them on. Upon returning you will see the outposts and their surrounding regions patrolled and maintained by SGS personnel.
Yeah, those small touches are nice and add some flavor, but to be fair some of those are barely noticeable (e.g. protectorate presence at Junkyard docks) or not noticeable at all, like the one you mentioned - once you finish reactivating the outposts there's no reason for going back to that area, so almost no one will ever see the SGS guards there. Once you're done with all quests, most areas/settlements become dead, with no reason to go back there except certain vendors, similar to FO2. You finish main Foundry quest = you'll only go back there for super steel or Kevin's stock, there's no new paths/quests/areas unlocked etc. Oculus questline remediates this a bit and spices things up though.
That said, it's still one of the best crpgs of last two decades, with super high replayability factor.