Because laws around digital intellectual property are profoundly different from physical goods, even when the goods are intellectual property like a book.<p>Consider a trivial example. I bought an iOS SSH app called prompt. The authors subsequently release a new version and removed the old one from the store. It works great on my phone and I decided decided to put it on another device. Guess what? It&#x27;s not on the App Store any more, and my options for using it are limited.