Those aren't comparable. There's no score-based admission to US High Schools, and for colleges the SAT/GRE is only one part of a broad application. There's no such thing as a score above which everyone is admitted, as there is in many Asian countries.
I don't think this is true, and I'm hesitant to go down this road on the internet but why not. My limited understanding of 'affirmative action' in the US is that it allows a schools to bin people based on specific categories, with race/ethnicity the one I think most people think of when discussing affirmative action. So maybe a school can legally bin based on gender if they wanted to hit a 50/50 ratio. A quick google search turns up some discussion around the topic, with the top hit describing a change in advertising instead of relying on affirmative action.
