Government encourages discrimination. The reason is that every group whose members are driven by self-interest (which most people in the world primarily are) and is completely unaccountable to anyone outside itself will discriminate against those who bear some superficial dissimilarity to the people inside the group. For an example of why this is, consider the following: there is a country populated by both black and white people but happens to be governed by mostly white ones. The goverment decides to raise taxes on black people, because the more taxes black people pay, the less white people have to pay to keep the government's wealth constant, and most of the senators are white, and "most people" is all that matters in a democracy. (The effect is stronger in a republic like America's where government officials are not themselves exempt from the law (supposedly), so they want to make the laws favor their own demographic.)
And you might argue that it'd be far easier for them to just give a tax break to government employees since that seems a lot easier to argue for, but suppose they already did that to the point where it's ridiculous and no one in the country can be convinced that government employees should pay less taxes. They would then look for a superficial trait that most of them share to draw lines with. Any existing racism in the country would be a huge help to them, so they would try to foster it.