Several things come to mind, it's going to depend on the generation you speak of, as well. Years ago, many people, black and white, didn't get the same amount of formal education as we do today.
Then, unfortunately, in some school systems, you had the whole "don't fail the black kids or you'll be called a racist" thing, so, even if you had students who weren't doing the work or making the grades, they got passed, just to not have a high black failure rate.
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When a person's achievements are seen to result only from racial, cultural or religious reasons the logic of determining their success is often faulty. Often the question is that a person of one group who observes a representative of another group doing better than themselves neglects the impacts of hard work, better study habits, supportive parents, better communication with teachers, better individual intelligence, better focus and clearly defined goals on achieving the success. There is often an implied belief that this isn't right as my group is better and should enjoy success as its birthright.