The letter grading system is meaningless to evaluate this test. It all depends on how difficult the test was written. If the test was written to be very easy would you say that it is amazing that every college earned an A?
I have had many physics and engineering tests where *nobody* scored higher than 60% and where the class mean was 40%. This doesn't mean that the class didn't understand the physics. It was just that the test was written extremely hard. These kind of tests weed out the people who don't know anything in the subject. If you don't study hard for one of those tests you will score 10%, and since it was graded on a curve you will get hammered ruthlessly.
I have also had to write tests when I was operating nuclear reactors in the Navy so that we had some expected average score and some expected failure rate. If too few people (fully qualified nuclear operators) were failing then the tests were too easy and they needed to be rewritten If too many were failing then the tests were too hard. And if the command didn't pay attention to this fact then outside of ship monitoring would.