Nobody likes exam. Then why do we take exam? Who have developed the exam?
They are Pedagogists, whose major is the Education. They have wanted to check whether or not a student understood well. Their purpose is actually not to reveal the shortcoming of a student, but to fill up a student who haven't understood yet. Exam is a measure stick for education. Why do they measure? Because they want to satisfy their original goal.
First of all, they make a certain amount of contents, and they want to let all of students know all of the contents. It is their original goal. In this sense, theoretical model is everybody gets 100 point, which looks all of them become same. If some of students failed to get 100 point, then it means a instructor need to teach them, to let them know all. Exam is feed back system to educate.
In real educational system, however, a school never feed back for their exam results. It is, simply saying, the process has finished just half of it. If they don't feed back, and don't make up, why do they take exam? Why does a person ask the price of bread, if he wouldn't buy it.
My point is that the purpose for exam in theory is much different from the purpose in real world. A society adopts exam system, in order to make Rank. And limited resource for education belongs to small group of 'High rank' people. Actually it should be opposite, according to the educational theory. Since 'Low rank' means they haven't understood well, and they need more education, the more resource should belong to them.
Why does our society behave in this way, which is much different from theory? At least they should have post process after exam, unless their purpose is making Rank. Why does a society want to give a rank to all of students? Who likes ranking system more? Why do we need rank? Because it is the easiest way to find a 'Better' employee.