Don't forget that even though it's a very bright white, it still has a measure of black in each gallon, which I've always taken to mean that there's a little bit of black (African American) in everything that the government chooses to display to the people, even if it's hidden in plain sight.
This works on two levels: most white paint you buy in the store is actually not the most white paint you can buy. You have to actually ask for paint to be tinted whiter, and the typical "white" paint at any store actually has a sizable amount of gray or black in it.
So, it's correct both literally and figuratively.
The government building is painted white. Its color is "Optic White" and the factory that manufactures it claims that it can "cover up any tint or stain." The symbolic message here one of racism and oppression: that whites control the rules (the government) and that they systematically seek to wipe out or cover up black identity.