As a fellow rural resident, I agree with everything you say here. There are days and sometimes WEEKS we get no mail. And UPS and FedEx do fine as long as there is no really bad weather. Drives me crazy. I always worry about the folks who rely on the USPS for meds and paychecks.I think we need a dependable US Postal Service. I'm glad to hear that someone has success with the USPS for their business. I have never bought chicks through the mail. I always get mine at the local Co-Op the day the hatchery truck delivers the day old chicks.
I have a few bones to pick with the USPS. I live out in the country, and it is not uncommon for me to see other people's mail in my mailbox from time to time. I just put the mail back into the mailbox and lift the flag for the carrier to pick it up the next day. I hope that my neighbors would do the same.
However, I have ordered packages from Amazon and a few get sent via USPS. The tracking service by the USPS is not very good where I live. I have had some packages reported as delivered, but I never see them. I have had some packages delivered but the USPS tracking lost track of them in their system. I cannot remember a time with tracking problems with UPS or FedEx, in comparison. IMHO, USPS needs to improve their tracking system to get to the level of UPS and FedEx.