Alcohol is totally legal for a child to drink in my state as long as consumed privately. It's only illegal for them to buy. My parents gave me alcohol all the time in order to teach me about it and the result was that I didn't really drink when I turned 21 or have any urge to sneak it.

That's exactly how I'm doing technology. I sign my kid up for kid accounts. And I apply parental controls.

Given the ease with which kids who want them can get any of those things in schools, it's not clear that the government ban is actually doing anything of significance or that the reduction in usage isn't more a result of convincing people that those things are actually bad for them so they choose not to partake despite the continued widespread availability.

Notice that consumption of those things is also down for adults even though adults are not banned from getting them.

I’m sorry in what world is age restriction effective at keeping teens away from alcohol? Are you from the 60s?

Doesn't seem to be a universal truth to me. As a teenager I had rather easy access to both cigarettes and alcohol in spite of usual age-restrictions legally imposed. I didn't care what gov't thinks about it. I did care about what my parents would do if I caught drunk though. That was my real barrier.