Lesson #2012 - Opium

Never forget that in the Wizard of Oz, Dorothy and her friends are assaulted by poppy flowers, essentially saying they were assaulted by opium. As if the general storyline isn't drug-inspired enough, it basically has to be written right in. Why not just have them try various random food and drink and have their perception go all askew? Why not just call it the prequel to The Wire that it so clearly is?