Also because Dot has mentioned twice to Roy that she was going to kill him.
There have been many odd things, especially if it's supposed to be 2019 or whatever it references to the timeline at the beginning. Cameras don't really seem to exist for one, and people move around regardless with way too much ease. But they do this in all good guy/bad guy movies. I see cameras everywhere, outside of homes, inside of homes, inside of homes facing outside, in cars, on bicycle helmets, all the way down the road and at intersections, which was the same in 2019, aside from maybe dashboard cams. But this isn't a big city, so maybe that gets a pass. Roy and his son fuck too much stuff up regularly not to have visible trails all over the place. They're not discreet or quiet.
The lawyer had to know he was going up to die--alone, didn't notify anybody, early evening, unarmed, to threat bargain with the devil. It was a suicide mission.
Dot goes into the room and makes a call facing away from the door? Then leaves the gun outside at the well/trough. WTF. Nobody hears the shots at the trough?
Anybody that watched David Koresh's compound explode knows that this isn't going to end well for them. There would be a larger army for one, and snipers. Roy just rides around on a horse, devil may care. If the son wanders into camp, they have to divide--a leader that loses his son, which then shows up blinded and disowned has to be a bad leadership sign.