Some schools the issue is teacher quality. Some is curriculum and resources. Some is external factors like food insecurity, housing, or crime.
It's weird like that.
After decades in education, I can tell you that the same five ideas get rehashed every six to eight years. And we ignore that our education system is nothing but a reflection of society in the US.
If you have money and connections, everything is groovy. If you don't, it's not.
I generally find myself pro-organized labor, but when we start reducing in-group competitiveness for high pay, into low pay alternatives like seniority systems, job security becoming job permanence, or outright hostility to technology, that's when I start seeing the model break down.
The “central role of education in our society” seems a lot like a slogan that is, at best, aspirational, and at worst false-meritocracy cover for persistent structural inequality.
While educational performance and attainment seems to correlate a lot with success, differences in educational interventions and methods seem to do a lot less: those measures that seem to matter seem to themselves largely be a function of who you are and what your home environment is. Its not clear that education, particularly K-12, is doing a lot more than measuring structural advantage.
Given the central role of education in our society, teachers should absolutely be paid more.