Back in RDR2, I was trying to think about how you could even go about avoiding mass murder, as the game kinda forces it on you either specifically ("kill the rest of the enemies" objective in a mission) or implicitly ("we put you in a rough spot because the wanted mechanics are borked, and you have no chance of running from these enemies"). But then I thought "well, I suppose you could just be awesome and disarm them all", but as it turns out... no, no you can't.
I thought I was just completely misunderstanding how disarming worked and that I was shooting the wrong spot on their arm... you can tag their guns specifically in deadeye mode, but that just caused the bullet to ricochet off their weapon while they maintain their grip.
Turns out you simply cannot disarm certain enemies, such as: lawmen, certain mission enemies, anyone riding a horse.
So really, don't even try to rob people out on the country roads... If they pull a gun on you the only thing you can do is kill them, since they can't be disarmed, outside of switching to your lasso and pulling them down off the horse. And threatening someone to rob them, having them pull a gun on you and you defending yourself will cause more honor loss than just wasting them from a distance and looting the corpse.
Dammit game, I *want* to like you!
EDIT: Oh, yeah, all of the shopkeepers in one town are now heavily bandaged and are all furious with me. I've never touched any of them, either with hands or with bullets.
There was a plot mission shootout in that town just before this happened though, but all the enemies were a specific faction of plot enemies, not the townsfolk. If the game somehow screwed up and flagged those mission mooks (or at least their bodies) as the town's actual populace, I will be irritated.