Proprietary JailsOther examples of proprietary malware
Here are examples of proprietary systems that are jails—they do not allow the user to freely install applications. The image of the iPrison illustrates this issue.
These systems are platforms for censorship imposed by the company that owns the system. Selling products designed as platforms for a company to impose censorship ought to be forbidden by law, but it isn't.
iOS, the operating system of the Apple iThings, is a jail. Apple introduced the practice of designing general purposes computers as jails for their users.
Apple used this censorship power in 2014 to ban all bitcoin apps for the iThings for a time. It also banned a game about growing marijuana, while permitting Games about other crimes such as killing people. Perhaps Apple considers killing more acceptable than marijuana.
Here is an article about the code signing that the iThings use to lock up the user.
Game consoles are jails, too: no game can run on the console unless the console's manufacturer has authorized it. Alas, I can't find a article to cite as a reference for this fact. Please inform us if you know of one.