I'd guess the number of packages that potentially smell like weed is pretty insane these days.

So the USPS, who took 3 weeks to send my priority mail package (containing no weed) about 350 miles, is going to flag all those packages (or even a worthwhile fraction of them), set them aside, get a warrant, open them, and then what?

First, they'll be wrong some of the time because it's jackasses sending delta8 hemp or whatnot.

Meanwhile they've added another complication to their already clearly shit scheduling and routing process, and they've done all this to enforce drug laws, which is not even a component of their purpose as an organization?

Don't ask don't tell makes much more sense, and I'm willing to bet that except in egregious cases where someone tries to send a pallet of weed or something, that's what they every shipping company does, except the occasional try-hard to pulls the alarm on something that smells funny the first time, then gets told to stop wasting everyone's time.

We're on the cusp of becoming post-prohibition with weed nationally. There is literally no upside to USPS or any shipping organization proactively looking for random weed shipments in packages.