I'm pretty sure the order for these in France is
- sex (age of "sexual majority" is 15)
- driving (learner) at 16
- driving (full license), voting, getting married and buying liquor at 18
However, the alcohol thing is just for buying it. There is no minimum age for alcohol consumption. It's just illegal to sell alcohol to a minor unless their parents are right there.
It's not that well enforced though. When I worked in McDonald's, if someone ordered beer as their drink and looked like they were 16 or more we just honored the order. I've never been asked for ID when buying alcohol either and it's sold in regular grocery stores, with liquor in its own section and "lesser" drinks (cider, beer) in the same isle as juice. (In Canada where I've lived too, alcohol is only sold in alcohol stores).
Note that for the first point I didn't say "age of consent" because there are two different crimes here, depending on consent. The age of consent is in practice 12 or so, meaning that under that age it will be considered rape either way, but having sex with someone aged between 12 and 15 is a crime and punished with prison either way, but with a less heavy penalty if consent is established.
That law has always seemed weird to me. It's basically saying "we state that anyone older than 12 is old enough to give their consent. However it's still a crime to have sex with them when they consent if they're less than 15." It's kind of a weird double standard.
Anyways, I agree that alcohol isn't something that requires you to be 21. I had alcohol every so often as a kid in family meals, for instance I always had champagne (a sip) at Christmas for as long as I remember, and cider in February for Chandeleur (a glass, doux).
To this day I'm not a drinker, I wouldn't say I even have a glass a year, and I've never binge drunk either. I think it's good to learn about alcohol with your family because then it's just a normal food (well, drink) and not an act of rebellion or something. Plus in small quantities several alcoholic drinks have been shows to be good for you.
I also think it's good to be familiar with the dangers of alcohol and know to limit yourself and how much you can take before you start driving. I mean, this way when you start driving you already know how not to abuse alcohol, while otherwise if you start drinking while you already drive, you're more likely to have a bit too much alcohol and drink and drive (people don't realise how fast your reflexes go away, even if you're not drunk).
I think it reflects the different cultures well though. You can drive earlier in places where having a car is more important and more useful. You can drink earlier in places where alcohol is more part of the culture.