Soup,
That is another advantage of the post office; they will cash a USPS money order. On the subject of who is cheaper, I received a small package from a business who sent it by UPS at a cost of about $12. The next time I ordered the same thing, from the same company, they sent it by USPS (without me asking) and it cost about $5. With the computer it is easy to check the USPS, FEDEX, UPS, etc and see who is the cheapest. The only package I have ever had lost, was shipped by UPS. In fairness, I once received a rod, in a metal tube, packed inside a long cardboard box, shipped by the USPS arrive in a L shape.

Standard disclosure, I am not employed by the USPS, FEDEX, UPS, etc.