Because their labor can be very cheaply duplicated by broadcasting the game to millions of spectators.
*> Where's the money actually coming from?
Ads, merchandising, and ticket sales, like you note.
Professional sports players are, economically, in the same category as musicians and actors. They produce media and the digital era means media can be duplicated at virtually no cost, so the value of their labor can be easily multiplied by a very large constant.
Police, doctors, and teachers provide their labor to individual humans in realspace which is much harder to scale so, unfortunately, their salaries reflect that.
I agree for all the examples you give, there's nothing clear like there is for athletes and artists.
For what it's worth NBA has actually taken the opposite stance from the other leagues in terms of highlights online. See https://www.businessinsider.com/adam-silver-nba-ok-highlight...
I don't know how to fix the teacher's pay. It's just unfortunate that by comparison they make pennies.
Without even a cent in extra tax.
Must be why NFL, NBA etc get so fuckin salty when people upload highlight reels and stuff to youtube.
I can't think of anyway to similarly monetize teaching and I really don't think anybody should go down that route, it sounds terrifying. But how do you convince a bunch of people watching football, which kinda costs them either nothing or like 90$ a month for their cable subscription, that they should also spend a % of their income on teachers?