I had a conversation with a cousin who is attending a college. She mentioned that she was having to take a course in organic chemistry. This course is so difficult that it is expected that students will fail the first time through and will have to repeat it. A student who passes with a C+ or B- the first time is considered extremely smart.
Whether intentionally or otherwise, such courses as this serve the function of qualifying students for entry into a related profession, creating barriers to entry and restricting the numbers of students who can qualify. This is usually considered a good thing by professionals, but not so good by everyone else.