USPS is bad for many other reasons, too. The post office where I live (a major city) is basically open in a narrow window from 8:30 to 5:00 on weekdays and a short four-hour window on Saturday. Need to ship something out? Unless it can wait until Saturday, you'd better plan to take time off from work unless you're willing to leave it on the side of the road for hours. And if the sender requests that something be held for pickup, that means you have to pick it up during that window, too. By contrast, there's a local UPS store that's open until 7 M-F and until 5 on Saturday, and a major FedEx depot that's open until 8 M-F and 5 on Saturday. It's just a much better experience.
And USPS tracking is borderline useless. It typically provides little more than a delivery confirmation. UPS and FedEx track it at every point along the way so that you know almost exactly where your package is at all times, and so do they. This makes package loss much less likely.