My point was that elections here are almost always about improving public schools, but the government has not been able to over the course of decades. Call their stewardship what you will. Purposeful sabotage, accidental sabotage, whatever, doesn't really matter to me. What matter is that the government is not capable of enacting the voters will of having good public schools, which is why charters are so popular.
Keep in mind that the North also had it's share of segregation and discrimination against poor(and by proxy Irish, Poles etc) and people of colour. It includes schools.
Also property tax as way of funding schools is awful.
And as for the overwhelmingly blue thing, that’s another simplistic narrative. Substantive politics in the US has very little to do with the party that you vote for, as the parties agree on 99% of the particulars, if not the rhetoric. Illinois is one of the bluest states in America and Chicago one of the bluest cities, and yet Rahm Emmanuel ran under a dem regime one of the most infamous regimes of city-wide austerity in recent memory. The Daleys were out and out corrupt racists. I could go on.
You should only compare to countries with a similar cost structure.