"Drinking, smoking, voting, joining the military should all be the same age, and perhaps even the legal age of sexual consent too. It's legal adulthood. If you are old enough at 18 to join the army, you are old enough to buy a pint of beer or have a glass of wine in a restaurant."
That logic doesn't follow. Just because someone can voluntarily sign up for the army doesn't mean that he or she should be able to buy a beer. There is no connection. In this country, you're not able to rent a car until age 25. It's all about risk and responsibility. The fact that you want everyone to be able to drink a beer THE SAME DAY they can legally drive is amazing. Here's a license to drive...now go abuse your body with alcohol and then drive home.
I know that in Great Britain, you do have a tremendous problem with teenage drinking and fighting in the streets...that teaches us, what, that it's better than our system? At least here we have GRADUAL steps toward responsibility. Due to the dangers associated with alcohol, whether it is with driving, fighting, or anything regarding decisions we make (alcohol clearly clouds those decisions), we don't allow people to get everything handed to them all at once...many kids will abuse it if they get things all at once, as in your country. First, you're able to vote in civil society at age 18. Then, you can smoke (if you want to) at age 19. Then, you can drink (again, if you want to) at age 21. You can then rent a car at 25. You get gradual levels of responsibility, and it's up to you to choose to live by them or against them. Wouldn't it be great if we could do everything all at once? Sure, but it wouldn't be the safest thing to do. Isn't safety the #1 goal here? We're talking about 18-year old kids here...what 18-year old do you think is capable of making all of these life-changing decisions at once at that magical age?