Air charter operators are governed by the federal government, which give out and control the charters. The charter is given to "serve the people of the area."
Big game outfitters are a major source of air charter business in large areas of the north. Thus, if the outfitter is paying the charter service for a lot of trips to sheep lake, the charter operator will do his best to keep the outfitter happy.
If a non guided hunter asks the pilot where a good lake is to fly to into for mountain sheep, the pilot will never tell him, "Sheep Lake."
But if the non guided hunter contacts the charter operator and tells him they want to be flown into Sheep Lake, they will be flown into Sheep Lake.
Any hunter being refused a flight into a lake to hunt, because of the outfitter there, can contact the federal agency governing air services and the charter operator will have some serious questions to answer.
The charter operator was given his charter licence to serve the area and he/she must do so, or run a high risk of losing their charter.