>The most likely reason they did not do that, is probably because it just did not occur to them.
Is your stated reason ("it just did not occur to them") more likely than "they didn't have the opportunity to take those steps because of (economics/insert reason)"? A quick Google search give this link: http://www.brookings.edu/articles/1998/spring_education_darl... which indicated that in the 1990's, minority students generally had access to fewer or lower-quality resources than white students.
Is your stated reason ("it just did not occur to them") more likely than "they didn't have the opportunity to take those steps because of (economics/insert reason)"? A quick Google search give this link: http://www.brookings.edu/articles/1998/spring_education_darl... which indicated that in the 1990's, minority students generally had access to fewer or lower-quality resources than white students.