@lcamtuflcamtuf
I mean, the "the method exists it's impossible to stop crime" argument has varying degrees of success based on:
1. ease of material access (smuggling some things is harder than others)
2. ease of hiding use / storage
3. ease of washing the spoils / selling to the clean market so to speak
4. penalties / enforcement being serious enough to not risk it
5. alternatives being cheap enough and higher quality to use instead