I don't really know much about if there is any alcoholism problem, drinking is pretty much a big part of our culture so what some people in other places would define as alcoholism we would probably not haha
There's no warning signs about the check ID thing as well, the cashiers are just told to check. I'm 17 and look pretty much like my age, but I have only been asked for ID once when I was buying a beer to celebrate an exam at like 2 PM, so the cashier was an adult and probably didnt want to risk anything..
But other than that I've been buying stuff like vodka and cigarettes/snus on a weekly basis without ever being asked.
The only place I ever getasked for ID here is in clubs and bars, but as a solution we just go clubbing/pubbing on thursdays since they usually don't have as much security compared to friday and saturday and therefore don't bother check ID (at least in bars)..