What's the point of speaking in general? I see your point about athletes vs teachers, but you said in general. Is that the specific comparison you want to discuss?
I know of many jobs that have thousands on the waiting list for a handful of positions that do not require much specific pre-training (1-2 years of community college, 2 years similar experience, or sometimes even just high school), that pay far above the median (close to quite a few league minimums, especially when benefits are accounted for). On the job training may take 6 months to a year, so all the positions couldn't be IMMEDIATELY filled with untrained people, but there is really not that much specialization. There are FAR too many people qualified for it to simply be based on skill (especially since the required skills aren't that uncommon), so it almost comes down to a lottery. In this case these are companies that make huge profits, so similar to teams that can pay professional athletes because fans are willing to pay a large amount of money, minus the very specialized skillset.
There are also private schools, where people can choose to pay large sums of money for eduction vs government funded. I'm not sure if you can ignore this small percentage. By number of people it is small, but difference in income might be significant.
I'm sorry that I didn't follow your guidelines, but to me it is pointless if not impossible. For me, any general statement would be too general to be of any value. Maybe I could make the paragraph itself appear to be concise by keeping it short, but the description could never be.