This does not mean that the students did not learn anything. It means that they did not learn enough, or the right things to succeed in college. That is why there needs to be a national core curriculum of subjects that everyone must master to graduate, and that there be adequate competency tests to assure that this happens. This has been done in other countries and could be done here.
Most of the students that entered my college were poor readers and perfectly awful at math. Few could tell me how I determined grades on tests. For example, if you missed 12 of 35 questions, what is the percentage correct? What is the grade on a ten point scale? (65.7%, D)
The college got a large grant to provide tutors and computer programs in a lab to help students. There were 35 computers and one or two tutors available from 8:00AM until 5 PM,until no one showed up before 8:00 AM for a month, then they went from 9:00 to 6:30.
There were rarely more than three students in the lab. At least 70% of the freshmen scored below the minimum HS completion requirements for the State of Florida.
Unless race has something to do with gumption, this is not a racial problem. My experience is that students do not study well or adequately, and they lack the will to challenge themselves to improve. The problem is always, what does the teacher do when a valid exam is given and 75% of the class fails? Do you fail them all?
Most school districts will fire a teacher if he fails 75% of the students.
So what happens is that grades are "curved".
I never curved any grades. I did give students a way to pass by providing an opportunity to score 100% on homework, by resubmitting it, and by giving daily grades for class participation. That way, those who missed too many classes failed themselves. I was considered to be a hard teacher.