The evidence is literally in the federal and state legislation passed since late 1800s to support public education with extreme prejudice toward women and minorities. And the subsequent battle to make the system inclusive, culminating with the 1964 Elementary and Secondary Education Act (commonly grouped with “civil rights acts”). And even this law is continuously reauthorized by both sides on the aisle in the name of less discrimination (most recently “No Child Left Behind” and “Every Student Succeeds”).
It is very true that “systemic discrimination” is an argument often parroted without evidence, especially in audiences that prefer rigorous scientific method to be persuaded. But it’s also true that counter arguments often lack evidence that systems are inclusive, and almost never take on anthropological context which take time and effort to build.
No argument here. Though there’s tough competition for some of those Nixon-Reagan era reauthorizations of ESEA which set the stage for standardized tests being the primary benchmark for everything (and priming the pump for education publishers to create/expand the test prep industry).