So tragedy of the commons says I want my, top performing, kid to be in a gifted only class to maximize his potential. But as a society I want all kids grouped, as bringing up the average knowledge of the country is a very good goal (and important when you realize things such as everyone gets 1 vote, no matter intelligence).
Teaching on the other hand is a relatively high status, low risk profession.
It can be, for teachers in comfortable suburban schools where the students are generally well behaved.
For teachers in dangerous, urban schools with severe disciplinary and even criminal issues (gangs, violence, drugs, etc), it is not so low-risk.
No. 9: Police and sheriff's patrol officers Fatalities per 100k: 18.0
No. 7: Refuse and recyclable material collectors Fatalities per 100k: 22.8
Feel free to look for statistics though.
Both spend a lot of time standing on the side of the road but far fewer people will perform absurd traffic maneuvers to pass a cop that's stopped in the right lane. IMO it's fair to infer that minute for minute standing on the side of the road behind a garbage truck with orange lights moving a trash bin is more dangerous than standing on the side of the road in front of a cruiser with blue lights harassing a motorist.
If you start moving garbage cans around at age 20 in a brand new truck there's a pretty fair chance you'll be looking to switch careers at about the same time they retire that truck. If you manhandle garbage cans around every day from 5-2 your body isn't going to last.
Teachers (along with police, fire and other municipal employees) are usually paid very well for the qualifications their work requires the time they put in and the wear on their bodies. Since most teaching positions are union jobs they're incredibly stable.
Personal anecdote: the teachers I've known all seem to be on the same career path. The start working in less wealth areas and slowly move upward until they land a well paying job that they like and has a pension plan. On the way up to that job they build their resumes, libraries of lesson plans and gain experience. IMO this makes sense, the schools with the most money to throw at teachers can be picky in hiring teachers and more effective at retaining them.
If it's just a "good teacher" or two in an institution that doesn't have that ethic, using more advanced students to help less advanced ones can exploit both groups.
Now, many public school teachers have to practice "guerrilla excellence" so it's a complex problem. But a kiddo who gets algebra doesn't necessarily get teaching it.
Luckily for me I had a great teacher who recognized my boredom and stuck me in a corner with some advanced algebra and trig books and told me to get to work. Much better for me and the other students.