The USPS is a really good example. Most of its modern problems are exclusively the result of politicians sabotaging it - given the constraints it operates under it's wildly successful. Even some foreigners I know have a positive view of the USPS because of their interactions with it (shipping goods to the US).

It offers good service to everyone in the US - even people living in the middle of nowhere - with fairly good delivery speeds and strong reliability. I can't remember the last time I had a package or mailpiece get lost, and I think I've had a package get damaged exactly once in my entire life.