I would buy the public service line if more then half of our mail didn't go straight into the trash. I am excited when I see a Fedex box on the door step. Not so much when I see a mail box full of junk addressed to current resident.
I can only guess that all that junk works. And I suppose it does... I keep the ones for local restaurants that deliver what may be good food...
Something the post office could do is to leverage their local infrastructure and work with the couriers. If I miss a UPS delivery, and have to ask nicely to get a 2nd delivery attempt. Picking up the package at the local post office would be a lot easier for everyone.