As a kid, when the US Mail came to the house, the mailman always blew a whistle (more like a pipe). That disappeared long before I moved to the country in 1965.
Some of the Rural Route carriers were contractors and provided their own vehicles and were paid by the mile, the total house count and the average piece count. They were the most punctual workers in the nation! 5 out of 6 days the mail was delivered within a 10 or 15 minute window. The sixth day was always a weekday, the delivery was by a higher grade postal letter carrier in a Post Office vehicle. it was usually the same person (for us Wednesday) and it would arrive between 10am and 6pm, if after 6, not at all!
Right after "The Blizzard of 1978" there had been no rural delivery for around a week. I saw the contractors drive up to mail boxes, dig them out then put a bundle of mail in. Slowing their progress to about 1/3 of normal. They worked to around Midnight, the next day went better but some mail boxed were burried at the bottom of the ditch where the snow plows had pushed them; the contract carriers repeated the whole process, On the third day of delivery it went differently. If your mail box was missing, and your driveway was clear the drove up to your house, and hand delivered your mail! Unbelievably good service!
In 2011 I had a stroke in the early fall. Around Thanksgiving, I was shuffling across the yard with 2 pieces of firewood to heat with (Took about 2 hours for me to fill the wood rack for the next 36 hours or so). Just before lunch time a Mail Jeep pulls in my yard and a 6'4" Black man, I had never seen before gets out. "Hi, I'm Omar, your new letter Carrier, I just wanted to introduce myself to you. Here is my card if you have any questions, just call my cell. Oh let me help you with that!" I had only heard tall tails from the 30's & 40's of RFD carriers being that helpful! When mail service was going downhill fast, Omar, was the best I've ever seen!
I moved to a condo almost 6 years ago, mail delivery is at a 400 mailbox hub at the front of the complex. Service is rude, never the same time twice, and we have to meet our neighbors to exchange misdelivered mail!
Ivan