As a society we have allowed our children to believe they are all not just above average but superior.
Because we're afraid to hurt anyone's fragile psyche, or not be loved, or because we're afraid of some nebulous retaliation if we aren't soft, we dish out A's and B's as if they were scoops of ice cream on a humid day, the equivalent of myriad certificates and trophies for we give our children for showing up so they don't feel "left out" in sports and innumerable other activities.
Grade Inflation is rampant throughout the educational system. A recent UCLA study revealed that although students are studying less than ever, grades of A- and A in high school classes are the most common grades. At many colleges, over half the class graduate with some kind of honors, making it difficult to distinguish the truly exceptional from the grade-exceptional. The pursuit in college is of grades, not knowledge, so it's not surprising that students are as adept at cheating as they are in hiding booze in dorm rooms.
At the university where I taught, last year's freshman class had an average SAT of 1004 in verbal and quantitative tests, making their achievement dead-center average for the nation. But their high school g.p.a. was 3.3, about a B+. Those who don't do well on the SAT shrug it off as "Well, like, y'know, I just kinda don't do good on tests."
At many colleges, at least one-third of incoming freshmen are enrolled in remedial courses. But they and the rest of the student body can graduate within six years by packaging a program of "cake" courses with watered down content.
At many colleges, the grades of "D" and "F" officially don't exist; at many colleges, students can even drop classes any time, just so they don't get a (horrors!) "C."