Stumbled upon this wikipedia article and I'm shocked: "In the United States, pre-algebra is usually taught in the 7th grade or 8th grade. " It's not particularly late or bad to teach pre-algebra in grade 7/8. It's just that it shows such an abysmal gap between public education and above-average education. Family with means manage to help their kids learn pre-algebra years before grade 7/8, getting them ready for AP courses or college-level courses before grade 8/9, so that they can complete all math AP courses plus more by grade 11.
Note it's not that AP courses are particularly useful. I'm just using that example to show how some kids can be really left behind. If it's not AP, it could be something else. And no, I don't think we can solve this problem by shouting racism.