[programbreeding]

I personally think they do actually track things, but I would guess the postal workers are held to some kind of metric for delivery times. I think if they know they don't have the time to actually deliver your package then they'll often mark it as delivered when it hasn't been, then they just deliver it the next day. In your case it sounds like maybe your package got lost somewhere in the truck after they had already marked it as delivered.

This is all speculation based on my experiences with USPS.

[takeda]

I had this happening to me as well.

It defeats the whole purpose of tracking.

If employees are doing this, this means something else should change, either extend delivery times, hire more people, optimize how things are done etc

[wlesieutre]

Agreed. And not to single out USPS here either, I've absolutely had FedEx drivers sneak up to the door to hang a "We attempted delivery" tag without ringing the bell. I assume they're running out of time and don't want to wait to see if someone answers the door or not.