I'm expecting a call from someone in Ayr, Ontario, so I'll get back to you with her opinion!
Mine is that 16 is too low. In Britain, there is no restriction on the power or engine size of car you can drive at 17, but there is for motorcycles. For those, you are, basically, restricted to bikes under 125cc at 17 and can only ride bigger bikes than that after two years riding the smaller ones (it's more complicated than that, but that's the essence of it).
I agree with the earlier post that 17 is too low for boys but 16 would be all right for girls! For safety, it ought to be 21 for boys. In practice, it is difficult for a 17 year-old to drive because the insurance cost is very high here. Young drivers,17-21, particularly males, are involved in far more accidents, and far more costly ones, than older drivers, and present far more danger to themselves, their passengers, and other road users. And this is why we restrict access to motorcycles; the prospect of a 17 year-old on a big bike is a frightening one.