I think you may be confusing the assumption that people are equal (blank slate) with treating people equally (not misapplying aggregate statistics to individual

I think you may be confusing the assumption that people are equal (blank slate) with treating people equally (not misapplying aggregate statistics to individuals and not being an asshole). The latter doesn't require the former. Some leftists might argue for a blank slate but I'm not even sure this is the majority view.