I deliver newspapers in Finland, so not quite the same thing of course. In any case I got quite a few chocolate gifts, some other candy, baked goods from one customer and a 40e tip from another. The last one’s a bit overkill especially since that customer lives in an apartment building but I’m not complaining. I’ve done a number of different routes during my career and in my experience it’s roughly 1-2% of customers who leave something for me at Christmas. Since they have no real obligation to do so, I’m very thankful for each and every little gift they leave even if it is just a chocolate bar. Even that shows they remember it’s an actual human being bringing them their newspaper. 
Got a lovely thank you note from our postal carrier for her Lebkuchen cookie chest and Starbucks card. Perhaps it’s that as a military family that moves a lot I’ve come to cherish positive personal connections while they last.
When I’ve gotten mail for a neighbor I just put it back in my box w/ the flag up. Then it doesn’t happen again for a long time.
From the USPS website:
*Employee Tipping and Gift-Receiving Policy
All postal employees, including carriers, must comply with the Standards of Ethical Conduct for Employees of the Executive Branch. Under these federal regulations, carriers are permitted to accept a gift worth $20 or less from a customer per occasion, such as Christmas. However, cash and cash equivalents, such as checks or gift cards that can be exchanged for cash, must never be accepted in any amount. Furthermore, no employee may accept more than $50 worth of gifts from any one customer in any one calendar year period.
*
No. Since I don’t have a personal relationship with him; I do not feel obligated. He’s (she?) is anonymous to me. If I were at a business where we had a chance be on a first name basis; then yes I would consider it.
We just moved this past summer, so we had a lot if bunched up mail in spurts. Our carrier has been an angel with that and all my husband’s specialty meds that have to be delivered, so I made her fudge. I always appreciate what they do, so why wouldn’t I at least do something to show them that?
What the hell is a USAican?
I don’t claim to speak for others, but personally, I’m a replicant.
Can you really not figure it out?
Unladen Swiss-Asian Pelican.
Hell no. The very notion of tipping a gov’t employee is absurd to me. Almost as absurd as the term USAicans.