Really, is there anything that comes in the mail on Saturday that couldn't wait until Monday?
The fact of the matter is that NOTHING particularly time sensitive comes in the mail. Yes, we do need mail service, but why not limit it to two times a week--say Tuesday and Saturday? Would it really make a difference?
The mail is a little like human food digestion. A lot of stuff goes in, a tiny amount of with actual nutritional value is extracted, and the rest gets excreted as waste.
In our household, the Curmudgeon processes the mail. More than 90% of it gets immediately dumped into the recycling bin. The rest goes into one of two piles: stuff that needs to get filed (eventually--usually on a rainy day), and stuff that needs some kind of action (mostly, bills). The action items get addressed about once a week.
Oh, and there are the magazines, but even the so-called newsweeklies are no longer all that timely--any real news we've already gotten off the net from our smartphone. Being old-fashioned, we like having magazines around, but waiting until tuesday, or Saturday, to receive them would be no big deal.
So, to those who oppose eliminating Saturday delivery, we say fine--let's keep Saturday, and get rid of most of the rest of the days!