This isn't wrong, but it's mildly misleading. Pax is mentioned right at the top, but glosses over that pax creates "ustar" format tar files, which is specified

This isn't wrong, but it's mildly misleading. Pax is mentioned right at the top, but glosses over that pax creates "ustar" format tar files, which is specified by POSIX.1-2001. ustar tar files are compatible with almost all tar archivers, and are in fact well-specified.