There's one main mail carrier who delivers your stuff and he's slacking. He'll continue to get away with this if you don't complain.
UPS and FedEx are no better. I guarantee if you had a problem with one of those services, you'd complain. I've had a FedEx guy park across the street from my house three times, only to not deliver my laptop (I think he was just letting his truck get a GPS fix on him being there) and I only finally got it when I chased the truck and then his eyes were totally bloodshot. Guy didn't even get out of his damn truck.