Killdeer, I don't think anyone was blaming you for the shortcomings of the USPS. I would bet there are some UPS and FedEx workers on here as well and I don't think it is completely out of line for a person to share their woes with any of the big three shipping choices.
I am sure you are a very good mailmaam and take your job seriously, but the fact is not everybody does. In any profession, there will be those who strive to do good work and those that could care less about anything but the paycheck. Unfortunatey, the bad ones are the ones that give everybody a bad rap.