Doubt on a /tmp subdirectory owner

Am I missing something?

$ who am i
prime      pts/3        Jun 24 11:26    (:0.0)

$ whoami
prime

$ mkdir test

$ ll -d test
drwxr-xr-x   2 root     staff        117 Jun 24 11:28 test

$ ll -d /tmp
drwxrwxrwt  18 root     sys         2.2K Jun 24 11:28 /tmp

$ pkg info entire | grep Version
       Version: 0.5.11 (Oracle Solaris 11.1.8.4.0)

Why the directory owner is root (above in red)?
Shouldn't be prime?

Thanks in advance.