I knew the background of macOS coming with the acquisition of NeXT and I understood NeXT to have roots in BSD, but the verification of macOS 15 as UNIX was a little surprising.
While the back story is interesting, I’m not quite sure why Apple would bother with this at all? I suppose it’s nice to have a listing alongside of AIX and UnixWare. This claims it was done to avoid a lawsuit filed when Apple made claims about UNIX in advertising. I guess it was cheaper to modify macOS to be UNIX compatible than fight the lawsuit.
Standards are, in general, a good thing so it’s nice to know a script that is compatible with POSIX will work on both AIX and macOS, but they seem like very divergent customer bases and I doubt many scripts make that move.