It's coming to be hard to control the boarder between unallowed and allowed age. Just like alcohol which is OK after 18 years, kids drink it before this age as well, let's be realists. So with drugs it is going to be the same story.
The legalization of all drugs isn't going to do anything to help curb the influence of drug problems in the society. When they have access to drugs that easily, it is going to create a serious drug abuse problem in the society.