The other day, a couple of teenagers approached me. With a liquor store right beside us, they asked if I would purchase them 12 coolers. This does happen on occasion (and, yes, I decline). Now and then it occurs to me that I have yet to be approached by a youngster saying: "Sir, could you please score me some grass. My high school's dry".
The reason for that is simple: illegal drugs are easier for young people to get than legal ones. True today, this was also true when I was a teen. Even at the age of 13, any illegal drug you wanted was just one 14 year old away. Alcohol purchases, on the other hand, required some work. Fake ID, a (much) older friend, a willing adult, clued out parents who leave something around for their kids to swipe - all such endeavors were more labor intensive than copping illegal drugs from other kids.
Still - and this is understandable - many oppose legalization in the (false) belief that the very young would then have easier access to dope. Yet everything we've learned over the last few decades would suggest the opposite: while the safeguards placed on legal substances are not perfect, they at least have the effect of forcing youngsters to jump through a few extra hoops before getting the desired product.
Some protection is better than none and, so far, that is the best we've been able to do. And it's not hard to understand why. As soon as a product is banned outright, it goes underground and travels through channels that don't care about kids at all.
If you really want to protect children, maybe your own, consider how much harder it is for youngsters today to get drunk compared how easy it is for them to get high on marijuana, or even crack for that matter.
Sorry folks, but your authorities (political and other) have been lying to you for some time now. Drug prohibition is motivated by many interests and objectives - religious and moralistic zeal, economic exploitation, racism, and others - but protecting children has never had much to do with it.
Anyone seriously concerned with juvenile substance use and misuse should wake up and smell the coffee: legalization would at least afford youngsters some protection, whereas prohibition provides no protection at all.