They'd end up charging you the amount of money you'd make sending the package, that's how all these forms of rentierism work: Uber, Amazon, Apple, Shopify, etc. Private taxes they want to force onto people.

Must fight it at any opportunity. I can't imagine the economic value something like USPS brings to the country, likely trillions of trillions over it's lifespan. Something the corpos would never admit.