There are lots of ways to send packages. Stamps are used for letters, but a package tends to have various restrictions and so they get a shipping label which is supposed to be proof that you paid the correct postage without having to find the correct stamps which would be really annoying.

Business that ship a lot (which is probably most packages) don't go to the post office for each shipment. Instead they buy machines/printers/software/labels which allows them to print off the correct label, and also combines all the money into something they handle the money in one larger transaction. There are lots of options in the above for different needs, if you a shipping a package even once a week you should look into them - often you get a discount for something that is easy for you to do (sorting outgoing mail by zip code saves them a lot of money and so they will pass that on to you)

Because there are so many options you can find one option and duplicate it easily enough and it will take them a while to catch it.

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QGQBGdeZREunxLe an hour ago | parent [-]

I understand all of that but how are USPS even accepting a package with a counterfeit label? Wouldn't that show up immediately when the item is scanned?

	▲	bluGill 4 minutes ago \| parent \| next [-]
		I don't know what the modern rules are. I first encountered these machines in the mid-1990s when the obvious expectation is they are not connected to any form of network and you wouldn't be able to reconcile it now with the USPS as required a network connection then it should be trivial to require a unique barcode for everything and they can verify the barcode really exists but I suspect they haven't obviously did all the old machines that aren't network connected and so there's no way to verify
	▲	madaxe_again an hour ago \| parent \| prev [-]
		They’re possibly taking advantage of the international postage remuneration system. You ship something from, say, Pakistan. You pay them the postage, they put a label on your parcel, send it to the U.S. The USPS receive it, label it, deliver it, and note that the original collecting agency was overseas. Periodically, usually based on the inbound volume, they settle the net value with the other international postal union member. So - you ship from somewhere porous, with poor systems, it gets delivered, originating agency says “not ours, not paying”, and the USPS is left holding the bill.