I am also aware that 7+ people have been imprisoned for drug-related offences, but it appears neither of us can name any of them off the top of our heads.

This is an LLM-level misunderstanding of the answer you were given. This may be astonishing, but I've known at least seven people personally who have seen the inside of a cell for drug possession, use, or sales. The fact that I'm not going to list their names here is not evidence that I cannot name them.

You should google "actor arrested for drugs." I think you may find the seven names you need. Or 700.