And the Unix variants people use (the Open Source BSDs, most Linux distros) are indeed legally not Unix, just imitations. And they helped kill Officially Licensed Unix mostly dead. Not just through price competition, but through adaptability and stability you don't get when the software is a Product owned by a Company with Executives who get Big Ideas and Grand Synergies. Usually, the most the official maintainers can do is tell you that you're on your own with your weirdo patches they'll never merge, but that's a lot better than a proprietary company saying it will never happen in this life or the next. Ownership can be death, as people don't like living under a sword of Damocles where someone else can unilaterally end what they're doing.

Pedantically this is correct still.

You are not using UNIX unless you paid for a mac or iPhone (or higher cost machines like IBM AIX et.)

Linux is not a UNIX - it is not certified. Noone has paid for it to be certified.