Comment by bloak

You need to be 15 years and 9 months to apply for a provisional driving licence, but 17 to drive a car, in most cases, though I think there's an exception for some disabled people. You need to be 13 to give consent for processing of personal data. The age of criminal responsibility is 10 in England and Wales, but higher in Scotland, I think. It used to be 16 for getting married, with parents' consent (or without, in Scotland), but I think that's been raised. You can leave school on the last Friday of June in the school year (Sep-Aug) in which you turn 16, or something like that. There are lots of different age limits. I think the real answer to "Why 16?" is basically "Why not?".