Because it’s nontrivial to convert a grade into a ranking when everybody has the exact same grade. If you gave a test out and the average was 99 percent, you w

Because it’s nontrivial to convert a grade into a ranking when everybody has the exact same grade. If you gave a test out and the average was 99 percent, you would be ranking noise. They should make the course harder so even out the distribution of grades. The most informative distribution (ie maximum entropy) of grades is uniformly distributed. The least informative is when all grades are the same.