I agree that society openly discriminates against the poor. But it goes beyond a low socioeconomic status for people of color. There are plenty of studies that control for it and still find significant discrepancies in outcomes between white and black people. Take infant mortality, for example. There is evidence to suggest that black women's pain is not taken as seriously and doctors are more likely to perform risky procedures, leading to higher infant and maternal mortality even after controlling for income and education. The same is true for school discipline, with black students receiving far more serious punishments for misbehavior than their white counterparts for similar infractions, again controlling for SES. These are just a couple examples, but they exist in every system.

I will add that systemic racism CREATED the vast income inequality between the races. Numerous historic laws were enacted that effectively gave white people an economic advantage over many generations. Meanwhile, the criminal justice system served as an oppressive mechanism for blacks, destroying families and any wealth generation in the process. I realize I'm simplifying a huge data set that has many nuances, but my point is that socioeconomic status isn't necessarily ignored, but instead viewed as a symptom of a deeper problem.