"The Paranoid Style In American Politics" is probably the the best explanation of the fundamental forces that shape most of our politics. Playing to paranoia about "the enemy" has always been a successful tactic, and the war on drugs is simply the latest in a long line of "enemies".

"The commies are hiding everywhere" changed into "Gangs are in your town/school/neighborhood trying to get you kids hook on drugs". In modern times, a reasonable number of people see this pattern happening again with the paranoia about anting that looks Arab or Muslim: "We have to keep fighting the terrorists - don't you know that ISIS is hiding everywhere?". Unfortunately, a lot more people are fooled by the rhetoric when a politician starts spreading fear and loathing suggesting that "Those welfare queens are getting rich! It a complete free ride! 99.6% even have refrigerators!".[1]

It's an obvious trope once you learn to see it.

[1] http://www.cc.com/video-clips/jfmt11/the-daily-show-with-jon...