I don't think the goal here is to catch opioid users and criminalize them, but rather to try to cut off the illegal supply of opioids.

One of the root causes is supply. The book Dreamland is a pretty thorough explainer.

But I would assume the receiver is the most likely to be caught by systems like this and not the sender.

It might have been an initial cause, but treating it as a root cause now would exacerbate the problem. Every supply restriction makes it a more lucrative business to be in.

nailed it. this is the most backwards thing ever.

But damn, consider the potential lulz. If someone intentionally contaminated the postal system with fentanyl, an appreciable percentage of all packages might show up positive. I vaguely recall that this accidentally happened during the 2003 ricin attacks. One of the letters got ripped in machinery.

Fentanyl is very dangerous to handle. It wouldn't be "lulz" at all.

Well, if their plan is detecting opioid residues on the outsides of packages, they must be aiming for at least nanogram detection limits. Because they're counting on sloppiness in weighing and packaging. And those levels are far below toxicity thresholds, even for fentanyl.

Here's a fatal dose of fentanyl. It's 2mg.

https://www.drugabuse.gov/about-nida/noras-blog/2018/05/true...

Thats a "weaponizeable chemical" kind of scary. I mean, imagine if a dealer dumped something of this into the airduct of a public building or train station to get more customers...

That wouldn't get more customers it would just cause people to get high, sick, or dead. It's not like they would put a big calling card "like how you feel call this number"