I think the reasons why we drink as much or as little as we do has nothing to do with our age as much as it has to do with the wisdom we gained from our experience as to "why we drink".
For the most part, why and how much is really relative to who we are with and what we are doing when we drink.
I drink alone. By many "standards" that means I am a alcoholic. I do not drink with the intent of seeing how much I can drink or how big a buzz I can get.
Each society has its own "standards", I presume, based upon the general population, and/or the societal problems the alcohol produces.
Having a few beers and getting stinky drunk are two sides of the spectrum. I admit I have seen both sides and prefer the "few" over the "too many".
I like to drink my homebrew. I do not frequent bars. The last time I was in a bar was in Feb. I don't remember the time before that, but that has nothing to do with my memory, etc., just that it's been a long time.