Well the issue of cheating wasn't really a full security risk, as most of the cheaters would have passed anyways. But with a 90% pass rate, the idea if you got a 90%-92% = D
93%-95% = C
96%-97% = B
98%-100% = A
I am sure most of you who have been threw academia, with percentages so close that any number of factors can fluctuate your score by a few percentage.
Too tired from a night of studying. Too Hungry, too full, having to go pee, Feeling too anxious or too confidant....
Now a lot of these people taking the test worried their promotion prospects are tied to these test scores, so if you have a C or B it will look bad, compared to the next guy who got an A. While the next guy might have just had a better day that day. So Cheating was rampant, not in the dangerous level where they wouldn't have passed the test, but in making sure everyone had that little extra to get promoted when the time comes.