[illumin8]

Seems really cool. Serialization is the answer: manufacturer sends exact serial numbers electronically before shipping merchandise. Serial numbers are scanned with barcode readers on entry to fulfillment center and as they are picked/packed for delivery. There should be zero chance of co-mingling if done properly.

[binarysolo]

Amazon does do this - it's called Amazon Transparency. https://brandservices.amazon.com/transparency

[hobofan]

Given the incredible disregard for correct usage of GTINs by Amazon on Amazon.com I've seen in the past, I'm very surprised that this exists.