In Finland:
You can get a driving license at 18.
You can vote at 18.
You can buy tobacco at 18.
You can get a driver's license at 18.
You're conscripted at 18, though you can delay it up to 8 years (maybe a bit more or less). You can voluntarily start at 17, I think.
You can buy alcohol under 22% ABV at 18, and over that at 20.
Age of sexual consent I have no idea about, actually. I'd say probably 18.
So you pretty much get "the whole package" at 18, which is pretty logical to me. However, there are a few stupid things too:
1. You lose many of your benefits of being a child at 17. For example, child benefits stop being paid at 17, and as far as public transport is concerned, you're no longer a minor at 17. I'm 17
2. You can actually legally consume alcohol, and I think tobacco too, if you're a minor. However, there are strict laws that prohibit minors obtaining and possessing them. Eg. It's not legal to sell, or even give, the aforementioned products to a minor, and it's not legal for a minor to possess them. So whereas drinking alcohol is legal at under 18, there's no legal way for a minor to get that alcohol in the first place. So, in practice, the legal age of alcohol and tobacco is 18.