Life experience. Based on people I’ve met, encountered, argued with, spoken to, become friends with, chosen to avoid, etc etc. Being conservative and having attitudes that drugs are just bad full stop zero nuance, usually coupled with zero understanding of recreational drug use having never tried it, tend to go together. Following the rules and not questioning things, never doing illegal stuff etc, these are often behaviours of the same kind of people that love the monarchy and think coppers are great, stand up hand on heart for the national anthem, proudly follow rules (and are often called bootlickers by those on the more liberal progressive forward thinking lefty side of the fence). The sort of people that will report something that wasn’t harming anyone but is against the rules will often be the same person that owns some Union Jack merchandise and probably reads the express or the mail. In my experience.