But What Would We Do Without a Postal Service?

I recently bought two items on Ebay, one coming from Oregon, and the other from New Jersey. They were both shipped on the same day, the one from Oregon through UPS ground service, and the other through the Postal Service. Despite New Jersey only being about a 6 hour drive from here, the package is still going to take a week to get here, so the one coming from Oregon through a private carrier will cross the entire country in the same amount of time.

Why isn’t UPS allowed to carry mail again?