Having read a bit of history about how many modern national identities were constructed over the last three centuries, that's a disturbing sentence to see written so casually. Phrases like 'breaking down regional identities' and 'assimilating the youth into the "new" national identity' remind me of the forced assimilation of Sami peoples in Norway and Sweden or the historical efforts of French governments, both republican and monarchist, to ruthlessly crush regional languages in the name of a 'right' to common language.
A more accurate way to understand the purpose of public schooling might be: the objective of public school is to break down regional identities of old and forcibly assimilate the youth into the 'new' national identity so that, as adults, they will become a more compliant, fungible labor supply which is more easily legible to the state and elites.
That deeper purpose, which you either left unspoken or weren't aware of, is what many people in the US have against public schools. There are a lot of regional identities in America that don't have much in common with mine, but I'll stand should to shoulder with them against attitudes like yours and against the policies that follow from those attitudes. Doubly so in cases where their identities were crushed in the past, which is sadly common even in America.