Well, for one, at need-blind schools, AOs can still see whether a student has applied for financial aid or not. Further, SAT scores are highly correlated with wealth. Even if an admissions office is officially “need blind”, they still have pretty accurate ways to measure the applicants’ resources - parent occupations, expensive extra-curriculars and summer programs, wealthy school districts (or parents with the means to send kids to private schools). Come on, let’s not be naive.