Actually, the basis for outlawing substances had its foundations in racism.
Opium was made illegal as a method of harassing the Chinese in the late 19th century. Initially, only smoking opium was illegal -- because that's typically how the Chinese would use it. Marijuana was made illegal because it was associated with Mexicans (ever think about why "loco weed" only ever made its appearance in Looney Tunes with Mexican backgrounds?). Cocain was associated with blacks, I am told, although I haven't found the complete data on that one just yet.
That's really all there was to it. Alcohol couldn't endure the prohibition because alcohol is "the white man's drug" -- and too many white men were willing to fight to keep their drug of choice.