Let’s take the pessimistic stance that society is actively working to perpetually oppress the lower class and under privileged. If so then the fact that e.g. college AA is allowed to slip by but primary school support is opposed with death threats tells me that fixing primary school education is barking up the right tree or poking the hornets nest, what have you. The real threat is actual competition, which starts in the early years.
I tend to think is less of some insidious underbelly of society working to keep people oppressed and rather a more simple: good primary schools cost money and resources and we are ultimately selfish people who signal virtue yet balk come time to face reality and fund it. But that doesn't really change the conclusion. Democratize access to good primary school education. Increase funding and dismantle broken school district “gerrymandering” of funds allocation (in many cities rich communities produce rich and desirable primary schools because funds are allocated at the neighborhood level so it just perpetuates inequality). In my opinion the most effective thing a single concerned family can do would be to move to an under privileged neighborhood and send their kids to the public school there. Force yourself to confront reality and work to better the education for all. How many upper middle class virtue signaling anti racist parents (or parents to be) do you know who go gentrify a neighborhood and then send their kids to a charter school? Yeah. That’s literally SF in a nutshell for you.