As boulderjohn will point out... Colorado has the highest percentage of divers of any state in the US. Unless you count the Colorado river... it's about as landlocked as you can get.
Yes, but look at it from a shop/instructor "earning a living".
How do you hook new divers, by selling them on diving in Colorado or somewhere else. So the real revenue belongs to the resort.
Do you do all instruction in house or are many of the water portions done by referral somewhere else. Again losing revenue to the resort.
After you teach OW can you generate income allowing the student to refine skills at that level.. or is the main way by selling advanced courses too quickly.
Few instructors could expect to "earn a living" in a healthy way by providing dive instruction in that arena.
I'm a rehab assistant. In order to "earn a living" I need to go where the sick/injured people are, in large numbers. I could make a few bucks trying to offer my services in healthy locales like but could I really "earn a living"? No, it would be more like a hobby. I could work in the community by referral. Driving here for an hour and there for two; but that's a hard way to earn a living. It's more like part time work. No, if I want to "earn a living" I need to try to get a job at a facility or clinic where many sick or injured people congregate. I show up at 9 and work until 5 with 1/2 hour lunch and coffee breaks. a large number of working hours with little down or set up/travel time.
So, what I am saying is: It would be reasonable to expect an instructor to earn a living in a healthy way if they lived in Cozumel (for example), had a steady stream of clients and worked a regular set of hours. Teaching an evening here and there and on your weekends, traveling two or three hours to and from the water and more hours packing and unloading gear, and catching random groups of potential students is not the way to "earn a living". It's a part time job that leads to premature burnout.