I think that this is a symbolic letter. The YOU to whom the author speaks is a collective you (American women, as a whole). The statistics she quotes are true national metrics regarding the state of gender equality in our country. Do some women make more than their male counterparts? Probably so. Are some women living lives equal in every way to the men in their lives? Sure. Are some women happier not always striving for equality? Of course.
It has always been my view that part of equal rights was respecting the choices EVERY woman makes, whether you would choose the same or not. I do think that tends to be the thing that gets lost in a debate like this one.
But I really believe the author was trying to paint the overall landscape of the US in regards to gender, rather than saying that every injustice listed was true for every American woman.
Does that make sense?