Yeah, I assumed most of the world was at least 18. I was surprised when I moved to the US at 15 and could get a learner's permit and drive with an adult, and drive by myself at 16.
Yeah, I totally understand how it's necessary across many parts of the US. There's so much I couldn't have done in high school, like having a job, if I couldn't drive. I didn't live in a rural area, but between the sprawl and lack of public transportation...
Almost everywhere... there are very few places where you can drive before you're 18. There are like junuor permits and you can get them when you're 16, but your parrents are the ones responsible for your driving. Something happens, they get ringed. So, yeah, they can also not give you the license if you cause too much trouble.
In the US you don't get your full driver's license until 18. 16 is permit and requires an over 21 license driver with you, and 17 is a provisional license so it has restrictions on how late you can drive and how many people can be in the car.
I think that may be a state restriction. For sure you can get a permit at 15, and 16 should be provisional, but iirc the only restriction is that those under 18 cant drive after 11pm, atleast in FL.
Pretty sure the US allows individual states to set the ages. In Canada, it's provinces that set it. Lowest age I've ever heard of was 12 (for limited permits to move farm machinery along back roads in Saskatchewan, although that was decades ago and it might not still be a thing). I had a full and unrestricted license at 16, but the rules have changed since then.
Admittedly it's been a long time since this was relevant to me, so this may have changed, but where and when I grew up in the US you could get a learner's permit (unlimited driving with another qualified driver in the car) at 15 yrs and 9 mos, then a full license (able to drive by yourself and transport anyone over 18) at, I think, 16 and 6 mos. At 18 the restrictions on whom you could transport disappeared, but I've never heard of anyone paying attention to or enforcing those rules anyway.
There may also have been a restriction about driving after midnight, but I don't recall for sure.