“As described upthread, students are given grades and at the end of the semester the professor arbitrarily decides what letter grade to assign to it.” How does this differ from a humanities class where a student writes a term paper and the professor arbitrarily decides whether it’s good enough to get an A? If a STEM student gets all the problems correct, they know they got an A. How can the humanities student know they got an A? Only if the professor “liked” their paper.