A year or two ago, mail carriers started refusing packages without a pickup slip (they initial it and put it in your mailbox as a receipt). Easy enough to crank out in 2-3 minutes onine. Why? My carrier said because of theft (my response was I doubted anyone was going to risk their job and pension over a $20 amazon return).
With the latest increase in postal rates, carrier pickup is only allowed for priority or express mail packages. So media or parcel returns you're out of luck. My carrier picked the last package up anyway. Good luck stuffing these into the big blue mailboxes.
One reason I ship almost everything UPS is that if I need a pickup I don't pay -- I just order something using Amazon prime (a $10 book or CD I was probably going to get soon anyway) and they pick up in two days.
Time and gas are too valuable to be running around on routine packages.