Not to jump on the bandwagon, but I have no faith in FedEx these days. I ordered a mic stand the first part of the month from a retail establishment (not used). They shipped promptly and the package was scheduled for delivery July 5th (Sunday). Not sure WHY FedEx was delivering on a Sunday in the first place. I check tracking at 1:15 and it indicates the package was delivered at 1:10. I check my front step: no package. Walk around the front of my house: no package. Asked neighbors picking up debris from blowing up fireworks the night before: no FedEx truck came down our street. Checked front door camera footage: no one came to my door. I made a claim with FedEx and the fact the driver marked off the box as delivered and no signature was required, the claim is denied. I suspect the driver was hungover from partying the night before and had no desire to make deliveries on a Sunday so plenty of people's stuff got "delivered" but was subsequently pitched in the trash or given to friends. The retailer was top notch and sent me a replacement at no charge. I do not suspect it was a porch pirate or the camera would have picked up something. Screw FedEx.
The last is a very common occurrence with all carriers. Mark it delivered so they don't get dinged on their metrics, deliver it the next day. Though if they paid out enough claims they might figure out their incentivizing their drivers poorly, as clearly that is not the intended outcome.
I can't imagine a driver returning a truck to the depot with undelivered packages that were scanned as delivered keeping their job very long. Those DIAD devices they carry are live trackers. That's how you're notified a package has been delivered via email or text concurrent with the delivery. It's not like Newman on Seinfeld stuffing mail in his apartment because he had better stuff to do.