The cohort taking the SATs is an upper slice of all students, so its a different demographic from raw income statistics. The white-Asian income gap is different among SAT takers. A lot of the Asian high scorers are first and second generation and not established as wealthy yet, just like a lot of the Asians being excluded from the gifted program in the NYC public schools by DeBlasio's policy changes are not well off economically. According to the NYT. In any event, there's a worldwide IQ pattern with East Asians above whites above blacks and it holds true regardless of income. Asians right off the boat and poor white kids from Appalachia outscore children of wealthy black professionals on the tests. It's not all about socioeconomic status.
While the black median income is around 40k.Like most things in life more money equals better education.