One offs and unicorns. Doesn't help that the Colorado HS coaching pool is one the worst in the country.
High School football doesn't mean the same thing in Colorado as it does a lot of other places.
You go to a lot of communities in Texas, Georgia, Florida, Ohio, and some other states and more people in a town, even those without kids in school, know who the high school football coach is than know who the principle of the school is, the mayor, and it wouldn't be a surprise if he was better known than their representatives in Washington or the Governor.
Many years back the coach before mine in high school was hired away to coach a program in Texas.
In Colorado he had a full teaching load with one extra planning period to handle football stuff. He was on the regular teaching pay scale plus paid the yearly stipend as a varsity head coach. I'm sure with the time he put in that stipend worked out somewhere above minimum wage but his assistants may not have.
In Texas he was the second highest paid person in the building after the principle and the third highest in the district with the superintendant added.
His job was as a full time coach. He did teach one class per day just to keep his classroom skills active but he didn't have to.
Any kid who is big, fast, and athletic or some combination of those is raised expecting to play for the local high school. It's not like Colorado where some of the best athletes are busy skiing, mountain biking, or playing hackey sack.
Kids in those states grow up with a focus on football. A lot of the ones who have a love of the game but not the talent to continue playing turn to coaching. While Colorado schools have trouble filing a minimal staff those states have schools that have to turn away qualified volunteers because they have too many.
There are some really good coaches in Colorado but not very many and the quality of the competition doesn't force top coaches or players to up their game to continue competing.