I've been picking USPS media mail as my preferred shipper for a couple of years, now. For one thing, the USPS has always been more reliable and provided better service to me than UPS and FedEx. (Yes, I know a lot of people can't identify with that statement.) For another, they are faster than those services about 50% of the time.
Plus, media mail is usually dirt cheap, and it is often free. (Especially from Amazon and Bookpool.) If I don't need something immediately, I pick media mail.
But today I got an unexpected surprise: a package I had shipped by media mail can be tracked at stamps.com. That's a new feature, I think. Yet another service of the commercial providers that the USPS has duplicated.
I'm happy, for now. Some parts of the libertarian revolution can wait.