That's covered by Amazon in the shipping cost they pay to move from their warehouse to the USPS sorting facility. USPS isn't making any additional trips to not deliver packages. They drive out to the mailbox cluster every day except Sunday (a day which Amazon also said they'd deliver a package via USPS...) and go no further.

You have a cite for that waste? That's not remotely correct. The marginal cost to ship one package across the world is literally pennies, that's why our junk is so cheap. The cost to drive to one store for one shopping trip is two orders of magnitude higher.

Buy online and save the planet. I'm serious.