I'm not sure this is all that unpopular of an opinion anymore. Government schools have been in decline for decades, and a lot of people were exposed to the truth of just how dysfunctional they had become during covid lock downs. Perhaps before that more people still believed in the noble myth of public education, but I, at least, have seen more and more people agreeing with the sentiment you put forward, minus the statement about keeping teens out of the job market.

Historically, labor unions opposed child labor for reasons that a) they should be in school learning things and b) they work really cheaply since they're unskilled. Unions in the 1800s were pretty open about why they opposed child labor, and they always mentioned the corrosive effect of an underclass of unskilled labor. So yeah... people might not think about it much now. But if you repealed child labor laws, I'm pretty sure the unions would be trying to fund high schools EXPLICITLY so they could shape the structure of labor participation by cohort.