No, the issue is not zero sum but the trade off of equity versus equality of opportunity.
* In your class are 30 kids, one of which screams and interrupts the the teacher. Do you kick the bad actor out so the other 29 kids can learn, or do you keep the bad actor in so that no one can learn?
* In your class are 10 slow kids and 10 fast kids. Does the teacher go at a slow pace so that everyone learns the same amount or does the teacher go at a pace so that the fast kids learn the most and the slow kids are frustrated by things being over their heads?
The problem is that we have too many blank slate utopians who believe it is the respnsibility of teachers to ensure that everyone leaves school with the same knowledge, and simply don't recognize that different students have different abilities and tempers and different suitability for learning.
This fanatical belief, to which they cling despite all evidence, is absolutely devastating for our educational system and causes it to be grossly inefficient:
* We do not have a trade school system in the US because we hate "tracking", or the idea that some kids should go into a more academically focused track and others should go into a less academic/more hands on track. Thus everyone goes to a school that is chartered as college prep which just means that there are no good college prep schools and there are no good vocational schools. It sucks at both tasks, but at least everyone gets to pretend that they have the same possibilities at college as everyone else. Thus we have a shortage of skilled craftsmen and vocational work, which then forces businesses to import these even as more of the native population slides into poverty while immigrants, who were spared the US secondary educational system, do well.
* Given that there are wide and persistent academic differences between groups, yet the teachers have convinced themselves that differences can only be the result of lack of funding or racism, accelerated classes are being cancelled all across the country and testing regimes that show differences are being cancelled as well, which leads to more misallocation of resources as students are not routed to the education appropriate to them and then universities lack reliable information to make admissions decisions. Thus university education in the US is extremely inefficient as they must do remedial courses to catch up what students should have learned in high school. This inefficiency creates a shortage of high skilled workers, which again forces the businesses to import them as more of the native population slides into poverty while immigrants who attended more rational tertiary regimes do well.
* the idea that "everyone can be X if they just try hard enough" leads to enormous self-loathing on the part of students who are being lied to and forced to participate in classes not suited to them, all so teachers and administrators can cling to these utopian delusions. At the same time the notion that "everyone can be X if they try hard enough" is a mockery to gifted students who are intentionally denied the chance to maximize their potential because educators don't approve of their race or would rather eliminate gifted programs entirely than have their illusions of equity shattered.