It's not stand alone, it's part of Amazon. Or, more properly, thousands of independent contractors who do the business for Amazon. Amazon has been doing it for some time and it isn't meant to be a money maker but allow for a less expensive alternative to having the USPS, UPS, and Fed Ex deliver the packages for them.
Where does that happen?
Every city in the U.S. and no doubt a lot overseas as well.
Where else would you and I give a $billion to help cover the the cost of their deliveries, other than Amazon? Were already doing it!
Leaving aside for a moment that package deliveries is actually a money-maker for the USPS then go ahead a jack up the delivery price four-fold. That will ensure you won't be delivering any packages for Amazon, or any other retailer. All that business will go to the competition. Then what happens to the post office?
So they make money on the dedicated free delivery service. Why dont they pick cheap items, send them out free to customers and make their money on the delivery? Now that is one great system theyve got.