You need to prove your implicit premise, which is that "kids" couldn't get pot essentially at will -prior- to legal sales. Which is an asinine claim on its face for anyone who grew up here to make. Never been a user but even straitlaced nerdy me in Jr. High could have, should I have chosen to, gotten weed from any number of "friends of a friends." If anything it'd be harder now because my network of friends and associates is smaller.

The problem with claims that legalization and commercial sales will make things "worse" is that legal sales, as this article clearly states, have had zero effect on usage. Logically and practically, everyone who wanted to try weed already has. Thus, anyone who would, say, drive stoned already does. Any kids who want to will get it the same way we did (or could have), the stores are irrelevant to all that.

What the legal market offers is the ability to pay a bit more for consistency of price, product, and direct access not involving sketchy people.