[samatman]

Is it? I'm with you on gobsmackingly ancient, but it's "doesn't support long options" which I haven't bumped into. I do replace some coreutils, but not all of them.

What's a good example of such a utility?

[skissane]

For example, sed. macOS sed doesn't support long options. Not even --help or --version

(Running an older version of macOS so can't completely exclude this has been updated in a newer version, but I'd be surprised to learn that was true.)