We had far more invested in prohibition, with far more outright corruption (politicians on the take from bootleggers), but managed to end that somehow. The difference was that alcohol consumption was mainstream so ordinary voters cared about the impact of prohibition. Drug consumption is not mainstream and enforcement largely affects minorities, so ordinary voters don't care.
This is a must-see documentary, not just for its coverage of prohibition, but for the historical insights you can glean about American politics: http://www.pbs.org/kenburns/prohibition.
In a nutshell, prohibition was far more invasive and far more corrupt than today's drug war. Al Capone was a billionaire in today's money, and the drug lords of yore were willing to exert political influence in a way that maybe happens today in Mexico, but certainly does not in the U.S. Al Capone once walked into City Hall and pushed the Mayor of Cicero (which was a former independent city in the Chicago area) down the stairs and nobody touched him. Politicians and police were openly on the take from bootleggers in a way that is totally foreign to our modern sensibilities (unless you have any familiarity with the developing world).
