On a basic moral level, we obviously identify the injustice of racism as based upon the dehumanizing collectivization of human beings based upon superficial characteristics. As Dr. King phrased it perfectly, on the colour of their skin rather than the content of their character. Why any sort of collectivization of individual human beings is immoral should be just as understood in a greater moral context. Much racial discrimination in history has been imbued with the oppressed racial group being condemned to poverty. Division based upon wealth and indoctrinated purpose within the economic system inherently amounts to segregation defined. Dr. Martin Luther King, Jr., Rosa Parks and other civil rights were dangerous "domestic terrorists" for seeking to challenge them, like today's Occupiers, "battered by the storms of persecution and staggered by the winds of police brutality" for their efforts. Consider the modern United States. Though it includes all ethnic backgrounds, the overwhelming majority of the prison population comprises of young African-American males; in prisons run for profit, they are forced into slave labour on mass production lines, with the punishment of non-compliance being solitary confinement. Slavery in the United States by any definition or measure exists to a greater extent than it ever did in the 18th century, at least in a more industrialized and covert form.
The fundamental question we should ask ourselves is this: how do modern hierarchies of control differentiate from racial prejudice other than basing themselves upon stratification of economic control rather than ethnicity?