I'm sure you'll make some stupid statement about "leave alcohol out of this," but if you know of another substance whose sale is both banned and allowed in different places in this country, I'll gladly substitute. The point is your claim that legal substances are somehow easier for kids to buy. You can't support it.
There are no bootleggers for the same reason that minors favor drugs to alcohol. Alcohol is bulky. Legalizing drugs will make it easier for teens to make a few bucks selling drugs to minors. If you do not understand that you understand the teen drug culture not at all.