Here's a useful comparison between the US Postal Service and other carriers for various items. (Click image for larger views.) This is what anti-USPS politicians want to eliminate to create "space" for corporate interests.

The reason the Founders created the Post Office was to pull the nation together, North and South, urban and rural, later East and West. It has succeeded for 250 years. It is self-sufficient if Congress doesn't demand inefficiencies designed to ruin it.

It ain't broke; don't "fix" it.