Why is sudo insufficient when running bsdtar?

[1ZRfPNdkrrRI]

First, sorry for my username, I was having trouble getting the forum user creation page to cooperate (it kept saying one of more field was marked as spam, but wouldn't tell me which one, so I was changing names and emails until it worked).

In the instructions for creating a boot image (for Generic AArch64, but I assume the same advice is given for all platforms) we're told to run bsdtar as root, and not to use sudo, to preserve the extended file attributes. But looking at the bsdtar man page and source from libarchive-3.4.2 it seems that bsdtar just cares about the value returned by geteuid, which is 0 in either the sudo or run as root case. It uses that value to enable the preservation of extended attributes and ACLs by default when called for extraction.

So my question is, have I missed something that makes running with sudo insufficient?

Was that warning perhaps added at a time when bsdtar somehow cared about the distinction between running as root and sudo? The warning always trips me up, and I'd love to put my curiosity to rest.

Thanks,
Anton