> "Tough on crime" was always a dog whistle to signal to (most) voters that politicians were willing to lock up minorities for comparably minor crimes.
I think race in these discussions is a poor stand-in for the reality of the situation. It's convenient, because it's much more easily quantifiable than culture, and we in the US had laws calling out race until ~55 years ago. But, looking at today, cultural mores and attitudes are the more dominant factor.
Even liberal Minnesota has the highest (or one of) achievement gaps in education. Part is the high influx of immigrants, which introduces a lot of second-language barriers, but not all. See https://www.twincities.com/2017/08/18/15-years-later-mn-scho...
Looking at very rural, very white areas, you see very similar bad outcomes WRT education and crime. Some companies are willing to pay very good wages for workers, and are very short on staff, but cannot hire because so many of the candidates fail a drug test or won't take one. A teacher I know in rural Iowa has white children in kindergarten who know (and use) more swear words than most adults, and their parents (if they know more than one of them) have little interest in encouraging achievement in school. They'd rather blame the teacher for the child's bad behavior and grades.
Tough on crime was a misguided attempt to change the culture of drugs and violence. That culture is still glorified in popular music, and fueled by poverty. It destroys the potential for hope, and so leads to more hopelessness, which fuels the culture.
Yes, race plays a factor in all of this, but it's not the only factor, and I suspect (though know not where or even if it is possible to gather) that culture plays a far more significant role. I know several people who believe (or believed) in "Tough on Crime" and not one of them did so because of race, or to lock up minorities for minor crimes. They see families in their community torn apart by drugs and violence, drunk driving, and so on, and want it to stop.
Edit: I read / skimmed the article, and realized it mentioned growing segregation, but failed to mention an experiment run by Eden Prairie and Minneapolis, where students could voluntarily switch schools in an effort to de-segregate. The results were that those who took advantage of the switch were black students moving from suburban to urban schools, and minority white students in urban schools going out to the suburbs.