The compliance trope that a point-in-time-assessment can't be used to support a claim is kind of a lazy take. The certification explicitly states macOS v26.0 Tahoe.

While it's true that it wasn't always truly UNIX compliant, they put in the hard yards to become so (albeit to avoid a $200M lawsuit from The Open Group) [1]

[1] https://www.quora.com/What-goes-into-making-an-OS-to-be-Unix...

Im sorry, but i dont buy that. Unix certification has nothing to do with number of processes running or "efficiency"! The OS must be SUS compliant, i.e have all the core interfaces in place, all the correct utilities (awk, grep, vi, sed etc) and theres something about header files, filesystem requirements etc. even if the macOS submitted for certification is super trimmed down, it does not matter as long as its a true subset of what is shipped to consumers.

MacOS is certified UNIX i.e its "UNIX", like it or not. On this point the article is just wrong.