Hours of operation alone isn't killing the USPS but it's a symptom of the larger, some would say terminal, disease.
Like most people who work in cubicles, I work 8-5. The nearest PO to my home is open M-F 8-4:30. The next closest is open M-F 8-5 and Saturday 9-12. That means I've got a single 3-hour window if I need to pick up a package or do something that requires human interaction. If I happen to be out of town or busy during that short window, I have to wait until the next weekend.
As has been discussed before, the majority of a bank's income is not on personal checking and savings accounts. For most larger banks, it's an ancillary service that they really don't try that hard to compete for most of the time. The real money is in business accounts and lines of credit (both personal and business). Even so, my local bank is open 10-7 every weekday as well as Saturday mornings and Sunday afternoons.
They've come a long way with online address forwarding, usps.com/redelivery, and other online features, but the window hours are terrible and it's endemic of the USPS' apathy with regard to customer service.
