Drug manufacturers, like weed farmers (in countries other than the US, for one)? The only reason I am able to use weed as an example is because it pretty much has been normalized, but what about other drugs, say, psychedelics, ketamine, opiates? I would rather not get into the War on Drugs here, anyways.

What kind of police work are you envisaging?

The one being done right now without this law

Well for one, the FBI could investigate the list of Epstein's clients which they almost certainly have.

You’ve jumped the pond, this article is about Europe not the US

It's an example. You don't think Interpol and individual EU countries' police have similar options?

The fact that these things often end up brushed under the rug makes me doubt that the goal here is really to catch abusers.