is the monopolisation of ski instruction in the US.
As
@Mike Thomas said, it is not a monopoly of instruction at the mountain. Whether the resort/ski area is Vail, Aspen, Loveland or whatever Mom & Pop resort you list, they either own or lease the land and they pay for all of the improvements and daily upkeep including turning of the lifts, snowmaking, grooming and yes the ski school, which is indeed a profit center for them. Some resorts do allow outside instruction in, most do not because it is not in their financial interest. These outside instructors will also need to carry their own libalitity and rent space and get approval at the mountain, most cannot afford that.
As far as pay, it is paid at market rate, if an instructor does not like the pay at one resort, they can look to another resort or not instruct at all.
With all of that said ... the system is extremely broken and short sighted. Overall most resorts are just looking for a money grab and not concerned about the progression of the skier, if they were they would be looking to build loyalty in that student.
Where I have seen flaw, because there is a lack of instructors (either because of pay or need during a holiday week) when they take a (example) snowboard instructor, who might never have skied before, make them a ski instructor and after 5 days of "training" teaching beginners and charging that student the same as they would be charged if they had a LI or LII, that person is NOT getting their money's worth but that gets into the whole resorts treating the most important skier, the very first timer, by putting them in the hands of the least experienced employee, the rental shop kids who oversize marginal gear to the first time instructor, but that is a whole 'nuther talk show.
But to quote Inigo Montoya "You keep using that word, I don't think it means what you think it means"