USPS…….HOW MUCH?

Fwiw
I took a 4.7 lb box to UPS last Friday to ship headliner bows to TX. From Phila suburbs.
I was quoted $122 and change.
The buyer went on the usps site and punched in the specs and $155 was the quote to ship. I live a half mile from my local post office and while the buyer was checking the usps for a quote online I took the package to my local post office for a quote . The quote was $76 w/o insurance.
I didn’t check Fedx but technically they should be less expensive than ups since they are non union. However, it doesn’t seem to work out that way in my experience. Shipping cost have become painful!!