Welcome to the Era of Fake Products

Could this be mitigated if manufacturers included a "verify authenticity" QR code inside the packaging, with a URL incorporating a very large random number, that got flagged as "used" the first time someone browsed to it?

Counterfeiters would need to aquire large quantities of used packaging from consumers who don't bother checking the code.

That might be further mitigated by arranging it so the code is exposed during unpackaging, in a way that makes casual tampering obvious, but destroyed by completely unpacking the item.

Another "perk" is it makes it harder for Amazon to resell returns.

Yes, it's a cat and mouse game, but my gut says counterfeiters would simply move on to easier products. High value items could come with a bigger cat (eg. Challenge/Authenticate RFID tag).

Sounds like a weekend project. Think there's a market for this business idea?

Once you have the slightest desire to avoid Amazon you notice how easy it is. I order a ton of stuff from walmart.com and the only difference is it takes a couple more days to arrive.

Amazon, no wonder. I’ve stopped ordering from Amazon for this reason

No Amazon. If you can, contact the seller directly and agree with them the terms for buying and delivering. In most occasions they already have some standard for this.

Easy: stop shopping on amazon. It's a cesspool.

1. Buy local 2. If buying online, buy directly from the seller's own website and not via Amazon.