Your discussion of foreign kids not drinking is ridiculous. As someone who graduated college within the last few years, still lives in a college town, and spent a lot of time with foreign students (large groups of German, French, Colombian, Swedish, and Chinese) who were in the states for a semester, I can assure you of two things:
- The drinking age being 21 does serve as a deterrent to binge drinking.
- The foreign kids party just as hard (except some Asians, mostly because they get too drunk too quickly, turn red, and hyperventilate)
To my first point: under aged kids have to find someone else to buy their alcohol (assuming basic enforcement of ID law), which isn't impossible, but isn't easy enough to just write off. Older friends aren't always chomping at the bit to run to the liquor store and fill your order, and fake ID's aren't as ubiquitous as it seems, especially ones that look like you and aren't expired.
And since these kids can't drink legally in bars, the binging that they do engage in is done mostly at home or at a friend's home, which is a more controlled environment.
And to the second point: I once had a plastered French student ask me after his fifth shot whether our drinking age of 21 just caused Americans to go overboard when they did come of age, then turn 90 degrees and throw up on his dorm room floor. This was not abnormal. The French and the Colombians were the first ones to start drinking and the last ones to make it back to the dorms, and they were no less likely than the American kids to be found passed out in the hallways or subway seats. And their countries' drinking ages are 16 and 18, respectively.
Also to the second point: The country with the biggest binge drinking problems worldwide is the UK, where the drinking age is 18. If you travel in international vacation spots, the ones falling in the street with puke in their hair are not Americans, they're Brits, and the places they're binging? Wherever the alcohol is cheapest.
Writing off published studies because of your own assumptions without offering data to back those assumptions up, is just silly.