To be honest I would prefer addicts could get heroin prescribed. The primary danger of street drugs is the inconsistent purity and chemicals it’s cut with. If it was pharmaceutical grade and everyone prescribed was on a list, we would have fewer overdoses and a better understanding of who to put in treatment

That's because the reasoning does go in circles.

0) Zero tolerance! We still remember how it ended last time!

1) But ... pain medication helps against anything. From headaches to hernia to bone cancer (of course in some cases it's in a "die somewhat dignified" sense). And in quite a few cases it's the only thing that helps ... In the medical sense of "helping", after all medicine can't make people live forever so that can't be the goal. The goal is better quality of life, ie. mostly longer life, including the ability to live (think "sing, dance and play tennis") ... and not life at any cost.

The problem here is that this is an entirely correct argument. Some diseases are either incredibly painful or long-term painful. Bone cancer or hernia can serve as examples. We cannot really help such people (by that I mean: not in a way that the pain stops). So can we at least make their life livable?

2) This pain medication sure helps these very seriously ill people well. But X suffering is at least as bad as bone cancer! X then is everything from still serious diseases, psychological suffering, and of course this then goes down and down until someone points out pain medication also helps existential dread and lackluster parties.

Again, all of that ... is true. That's not the problem.

3) The medication becomes the problem. Mostly because of what people do to get money for their fix (and the crime, prostitution, ... that it leads to). But this is not the only problem. It makes people who broke a bone last week go skiing again. And ... I'm almost afraid to say it but you can increase the effect of morphine ... by damaging yourself. You can guess how that ends.

The problem is that pain medication, irrespective of whether it's physically ("biologically") addictive is addictive. Anybody who's had a serious pain for a week, say kidney stones, knows that they would have sacrificed their favorite cat for it to stop. The problem is not just that morphine is addictive. The problem is the pain, and the fact that pain medication is a temporary non-fix.

4) The medication becomes the problem, but doesn't just affect patients. It goes from "you know this funny thing happened to my niece ... and she did it to herself ..." to it destroys families, neighborhoods, childhoods ...

Result: ONLY ONE SOLUTION! ZERO TOLERANCE!

GOTO 1.