The root server can only see its own process as well, to make the root server less scary to use. "killall httpd" in the root server will kill httpd in the root server only.
The security context number 1 is reserved. This context can see all processes. The vserver package provides 3 little wrapper to help manage all the processes:
Those wrappers are simply doing
# The vpstree wrapper /usr/sbin/chcontext --ctx 1 pstree $*
Only root in the root server is allowed to "jump" into a specific context.