Exams are what 'real' grown-ups use to occupy all those aged between 5 and 25. As soon as children start school, they are given reading tests, maths quizzes and spelling checks. Throughout primary school, their ability is constantly monitored with a variety of in-school exams. Then at a certain age they get exams to tell them if they're clever enough to go to a grammar school, quickly followed by real life qualification exams. Then, slap bang wallop after that, another load of exams are thrown at them. If they've not been put off by all of that (and the last set of exams are good enough), they get to spend three more years getting a degree (which is determined by yet another exam).
So why all the exams? Perhaps it's just another way of keeping kids busy and, hopefully, off the streets. It can also be looked at as a form of toughening for young minds: if you can survive your first 25 years of life, you can survive almost anything that it throws at you after that.