I think you're misreading the symptom as the cause. What's claimed is that black people are arrested more, even if they don't commit more crimes. Thus, the statistics will not necessarily reflect reality, but rather the alleged bias in arrest and prosecution.

I agree with your final paragraph, though. We as a society have an obligation to try to correct all forms of injustice, whether it's biased enforcement and prosecution, cultural isolation, or financial immobility.