> UPS just handed my package off to USPS who put a note in my box saying that I could come to a Post Office, wait in a long line, then pick-up my package myself. WTF is this?

It's UPS Surepost. Shippers use it for packages that are price-sensitive but not time-sensitive.

You don't have to go to the post office to pick up the package. You can sign the release, and have them leave it at your door.

Ah the joys of "SmartPost". SmartPost is popular for residential deliveries in a large part because it doesn't have the residential surcharge which other options do. SmartPost shipments also generally don't have guaranteed delivery dates so they may be more likely to experience delays during peak load time (e.g. this month).

Something I wish I had in my (European) Amazon shipping a couple weeks ago - they used a package carrier instead of the postal service, which used to be the norm. I had to call to set up a new delivery to a work address a week later.