I don't think they are "fine" in all red states. I suspect there are two different factors at work here:
1. For many red states in the South, public schools in general are notoriously mediocre. In these states, it is probably true that black students aren't any worse than white students -- but most of these students (black and white) do poorly compared to public school students across the nation as a whole.
2. For red states in the Great Plains and Rocky Mountains, blacks are a very small portion of the population and are not clustered in urban dumps like New York City, Chicago, Philadelphia, Washington, etc. In these states, your average black student probably attends a predominantly white school. The influence of "ghetto culture" in schools isn't a factor in these states.
I doubt Arizona has a majority black school. A lot of people in the east don’t know about the demographics in the west. In California, 40% are Latino, 35% are white, 15% are Asian American or Pacific Islander, 5% are Black, 4% are multiracial. I suspect outside of the pockets of inner city blacks, California is maybe 2% black...and 40% Latino, and 15% Asian!
The whole “black/white divide crumbles when there are 3 times as many Asians as Blacks....