People really need to unlearn the propaganda of the public-school-as-good and see it for what it has always been.
It has always been:
a tool for colonisation, internally and externally. It enforced “national” languages and “correct” forms of “national” languages like German, English, French, or whatever. It denied communities their specific cultural attitudes, it denied them their specific dialects of a language, and it enforced a “national” attitude upon the children who were compelled to go. In places like the United States, it was used to homogenise and forcibly assimilate immigrants (especially those viewed as “less good”), and it was used to forcibly assimilate and commit wide-scale genocide against the Indigenous people who were already there. It continues to do these things, reinforcing “correct” values, and we can see that the schools and the people in them are more often than not “just following orders” even when those orders are unjust and harmful. (In Australia, it'd be wise to consider how schools were used against the Stolen Generations and how, even as they teach about Aboriginal peoples, they still reinforce the “correct” ways of being as being in line with white Australians.)
a tool for imperialism. Continuing from the colonial project, there has been a forceful push of linguistic supremacy. There's a reason so many people on this planet speak English now. It should be obvious what that is and why that is... and it's merely a signal and a symptom, not the goal. This doesn't mean it can't or won't change; there are other imperialist governments seeking to ensure that they can replace the others. And they are all finding ways to deal with implementing a positive view of themselves outside of their own borders, making it far easier for them to extend their reach.
a tool for punishment, both pre-emptive and after the fact. Children are segregated out of society for multiple years, only released back when they're “ready to participate” (though this age seems to be changing). Children cannot learn about the world, they cannot learn about their community, they cannot be autonomous if they're routinely segregated into a building where they are placed into an artificial community that has a handful of adults who maintain control over their every movement. Not to mention how often schools work with police forces, immigration agents, and militaries. This should worry everyone.