Author here, it's true that GNU tar auto-detects compression when specifying a local tarball to extract. However when piping a file stream to tar to extract it

Author here, it's true that GNU tar auto-detects compression when specifying a local tarball to extract. However when piping a file stream to tar to extract it actually doesn't auto-detect and fails if you don't explicitly specify a compression type. Should have made that more clear in the post.