That's because the teachers unions pump millions into the Democrat coffers each year.
If Democrats weren't racist they would support school choice because wherever it's tried Black kids do better and learn more.
But giving Black parents a choice threatens the union teachers in public schools whose pay is not impacted by their inability to actually teach Black children.
Perhaps, and this is just speculation, the Democrats of today believe what the Democrats of yesterday believed; namely that Blacks are inferior and can't be educated.
Or perhaps Democrats realize that if Blacks could get a decent education they'd realize how the Democrats are using them.
In any case only someone who really hates Blacks or who is totally uninformed--the case for most Democrat voters because they trust the media which never reports the truth about the issue-- could object to letting Black parents pick a school where their child would actually get an education.