Can't comment on Montana, never hunted there.
What I can confirm is that there's a lot of disrepectful and lazy hunters all over. Perhaps some states or localities have more than others. Making general conclusions with a broad brush without actual data is not helpful and nothing but a generalization based on an individual's personal experience and small sample size.
There's a lot of hunters that just don't want to put much time in. They want to drive to the first nearest spot and shoot birds. That's it. They don't care if someone else is already there either. No scouting, no driving around, nothing else. That applies for other forms of hunting too, not just upland. Unfortunately, this behavior, although very disrespectul, is not illegal. So the only thing stopping someone from engaging in it is their own personal morals.