binary(pkg/mpkg) package not creating system user accounts upon install

[bitpup]

when using 'port mpkg dbus' to create the binary package.

and installing on the target system with

sudo installer -pkg dbus-1.4.18.mpkg -target /

I find the corresponding system account 'messagebus' for this package is not created.

The same may also be true for other packages requiring system accounts, e.g. avahi

Assuming the packages are created successfully, is it correct to expect this behaviour?