If I am wrong here, then I think it's because my fundamental understanding of what constitutes racism is wrong. My understanding was it was simply a belief that superiority and inferiority were defined solely on skin color, or race. For example, Jim who is black is automatically inferior to Jim who is white, because of the skin tone.
That core belief was perpetuated in order to justify the inhumane violence of slavery, etc. and was supported by charlatans (probably some in good faith, as well) who believed in, what we now know is pure junk science, like phrenology and eugenics and the like. This was a more mainstream and common belief pattern of white Americans in the past.
At some point in the last half-a-dozen decades or thereabouts, I think the mainstream and common belief pattern of white America changed. No longer is there a core belief that blacks and whites (or any other number of colors and races) are different in specimen and characteristics and potential as defined by nature (racism). I think the shift is that the characteristics and abilities and potential is defined by environment, which is dictated by social class and/or socio-economics (remember, I was conflating the two upthread).
As I've stated, legacy racism is a reason or cause for the modern day intersectionality of black people and a lower social/socio-economic class, but what America is discriminating and prejudicing against isn't the race, it's the class (poor people behaviors).
The biggest distinction here being one can't change their race (despite the weirdos who have tried like Michael Jackson and Sammy Sosa and Rachel Dolezel), but one's socio-economic and social standing is dynamic and fluid.