I am not a member of this community, but I did comment on the question, so I thought I'd expand on my comment here. (In a broader sense, I am active on the Stack Exchange network in general and so what I say is based on that.)
To me, asking a question to make a point doesn't seem right. The Help Center for all sites says:
You should only ask practical, answerable questions based on actual
problems that you face.
Now, I think this isn't as clear as it could be. We run into issues of e.g. what makes something a "practical" question. But to me, part of what this means is that your question should be honest and not motivated by something like "trying to make people I disagree with look bad". The Help Center also says to avoid making posts where
your question is just a rant in disguise: “______ sucks, am I right?”
Reading your comments, I felt like your post is kind of like this:
It just seems strange that kids can buy any drug they want, but purchasing a regulated product is very hard for them to obtain.
if Marijuana was legal, then legislators could begin making rules to regulate whether it is sold to minors? But as it stands, such a rule is neither logical nor enforceable?
who knows, maybe someone will provide an answer that explains why drugs are better left in the hands of people who don't care whether someone is a child or not. Then I'll learn something new and everyone wins
It seems like your post is "Prohibition of drugs sucks, am I right?" in disguise.
Asking "Why isn't there legislation that requires (illegal) drug dealers to ID customers?" is a pretty silly question, as people have pointed out in the comments. If you post a silly question, you should be prepared for it to get downvotes. If what you really want to ask is "How do drug prohibitionists respond to arguments about legalization allowing increased regulation of drug dealers" then you should say that outright. Your question in its current format seems disingenuous, and I don't like that.
Note that there's no way for me to actually tell if a question-asker is being "honest" or not. So perhaps what I really want is just the appearance of honesty. I think it's fine to ask a question based on premises that you don't believe in, but you should try to make it look like you are asking the question from some understandable viewpoint that shows some research effort. The question you posted, "Why aren't drug dealers required to ID customers?", doesn't seem "plausible" in this way, which I think is why several commentators expressed confusion about the question.