I deal with small packages everyday at my work and I too agree that the USPS is the worst of the three, however, I only see problems on occasions. I think that, yes, they are unionized and lazy, but here in Florida, they do a pretty good job. Our local carrier always comes in the store, we know him by first name and the fact that his son is finishing up Marine Infanty School. I have usually had good interactions at the actual post offices locally, except maybe the wait as you would just see people go on break and leave their coworkers hanging with a rush of people.
I have had a package that was supposed to go from the west coast of Florida to the east coast of Florida (2 day priority) and when the customer called me to find out where it was and I tracked it, I found it on its way to Ashville, NC
and some lost packages that cost us some serious cash.
My favorite in Florida, and I hate to admit it, is the unionized UPS. They do an outstanding job for our rush orders. Overnight ground anywhere in the state except the Keys and the Panhandle. (A majority of our customers are on the East coast)