Actually age limits work better to keep stuff away from minors than total bans. And with good reason, if somebody is legally selling liquor to adults they have a license of some form. And part of that license means the cops will be sending in minors periodically to try to get illegal alcohol. It’s in the license holders best interest to enforce the laws, else he’ll be fined substantially, lose his license, maybe even face jail time. When you have legal income from selling the product you have a vested interest in NOT breaking the law.
Drug dealers on the other hand are already breaking the law. They aren’t licensed, the cops probably don’t know who they are or where they are. They have no vested interest in not selling to minors, no legal income is on the line. Every transaction for them is illegal, no reason not to make as many as possible.
Liquor license style drugs should, nothing is guaranteed in this world, make drugs harder for minors to get. Of course you know how kids are, they’ll figure out something else. Those who want to will, that’s how whippets were invented.
but libertarians also oppose age limits don’t they?