There is widespread violation of the law. Alcohol is not hard to come by on most college campuses, regardless of age. The law is incredibly difficult to enforce as well, since I tend to like to think that colleges have some respect for our privacy as students and won't do random searches and ID checks. But the simple fact that opposition is divided and short-lived prevents any serious organized opposition by students. This country is based on freedom of choice, and with that comes a huge amount of responsibility.
Freedom entails responsibility.
Take a look at European countries, where the drinking laws are far less strict. I don't know why, and it's not important, what I've seen is enough proof for me without understanding the different mentality completely. I simply see it as repeating the mistakes of Prohibition, only on a smaller scale. Studies about liquor-related arrests won't solve the problem, and neither will stricter laws. Prohibition doesn't work, and the only reason that no one will say anything about it is because of the way the law divides the potential opposition.