Really good points. Something I haven't thought about. I was lucky to have an older brother who probably got it from local growers, until he started growing his own out in the woods. But that was a small town with miles and miles of woods to grow things out of sight of the authorities. In the cities I can imagine it being much more like you describe which might include getting it from pushers ready to push them into narcotics or other dangerous drugs.
Now it's legalized in our state and you can get it from a government inspected dispensary. A bit safer I would hope.