Perhaps its because so many people under the age of 16 are little turds with no respect for authority
This is the attitude that lies behind this unfair and ridiculous law. As a teacher who has met 10's of thousands of people under 16 so far in my career, I can tell you that the vast majority of under-16's are pleasant, normal and just as interested in law and order as adults. Of course thre are those who could be described as above but very few of them. It is obvious that treating all of them as if they are "turds" will make more of them anti-social and erode their respect for authority.