The tests are standardized throughout the state, so colleges can judge students “on a curve”. If Cornell gets an application from two students, one from a private school, the other from a New York City public school, they don’t need to try to figure out whose A in algebra is more impressive.
When I was at Kent State, I loved grading on the curve! In my Physics class I was the only male. All the rest of the students were girls in Nursing School and the weren’t good at Physics! Not only did I meet some great girls, and have a lot of fun with them, my grade, without the curve would have been a C+. With the curve? Straight As!