USPS

[Gman]

This and many other factors.
If it wasn't for "junk mail" I would bet stamps would be 20-30 bucks each and packages would cost more in postage than the contents of the box 99% of the time.
"junk mail" keeps the USPS alive, and it hardly feels like a break when you see 20-30K going to the post office every week.... oh, and "junk mail" just got hit with a 7% postage increase this month.
"junk mail" is also delivered to the local post office, not picked up at the printing facility.

If that were the case, bulk mail would be the majority of the USPS revenue, which it has been documented is not the case. You might wish it to be so, but it simply isn't true. 1st class postage is also going up 5% this month.

The increase in postage this year is supposed to generate an extra $2 billion in annual revenue. The USPS lost $15.9 billion in fiscal year 2012. Doing away with Saturday delivery is estimated to save $1.9 billion/yr. Do the math. This isn't going to save the hemorrhaging patient.