Because two of the three most used OSs these days have made the GUI an integral part of their design, we seem to confuse what is in front of the user with the OS, whether it's a workflow application, a program launcher or a command prompt.

The UI in my car's entertainment system is not part of the QNX operating system that runs the devices (and talks to the main instrument panel to tell things like the current speed limit or the song that just started to play).

This is good UI/UX work, but it's a workflow app, a personal information manager and it really doesn't (or shouldn't) care too much about the unseen software and hardware that's supporting it - that's precisely the job of the OS.

Because it is an UNIX clone, almost all of them quite bad at any kind of UI/UX.

All major desktop OSes that people actually miss, have had a full stack experience for users and developers alike.

> Because it is an UNIX clone, almost all of them quite bad at any kind of UI/UX.

That's because the GUI is not a part of the OS. The GUI is not an integral part of macOS - it's just that Apple sells one bundled, the same way that Canonical and Red Hat bundle Gnome. We had a number of other OSs that made a similar decision, on Lisp machines, Smalltalk workstations, Apollo's DomainOS, and a couple others I can't remember. None of these survived to this day.

Ironically all that made that decision rule the desktop and mobile space, go figure.

Including macOS and NeXT, their POSIX layer is only meant to bring stuff into the platform, not to ever let it out again.

There is nothing of UNIX on Objective-C nor Swift.

The GUI is not an integral part of macOS and iOS is proof of that. Apple’s phone GUI is an entirely different UI, as is the Apple TV and the Apple Watch, all running on top of a Unix.

iOS nothing to do with macOS, other than sharing the kernel, which isn't UNIX to start with.

Additionally, iOS only supports a subset of UNIX.

Finally it is impossible to ship an iOS application only using the POSIX subset exposed in OS.

How many iOS apps have your ever shipped?

> Additionally, iOS only supports a subset of UNIX.

Of course. It only needs what the applications supposed to run on it need. The same is true about my car entertainment system - it probably doesn't have many tty's and doesn't really need more than one filesystem. Same, BTW, applies to Android - it's a Linux, but it's not really a desktop OS.

> How many iOS apps have your ever shipped?

Does it have any relevance to knowing the difference between an OS and a GUI?

Too many jargons and catch phrases and few precise definitions/example on how this OS or concept would actually work :\