the person that i smoked most often with as a teenager used to get it from his older brother.
we had a bit of a falling out, and the next friend i met got it from somebody he got in contact with through his older brother.
i was the oldest, and my dad wouldn't admit it, so i didn't have any contacts - i had to rely on my friends for it.
this is the reality: kids get it from family members or the family members of friends, not shady weirdos on school playgrounds. and, no amount of regulation, however well meaning, will stop somebody from smoking their kids or younger siblings, or their friends, when they feel the time is right.