In Australia the answer to this question is much simpler.
VFR is not actually a collision avoidance system, it is a set of rules for operating in VMC which is defined in our AIPs. If conditions do not meet those requirements, then it is IMC which requires an instrument rating and is to be flown under IFR.
Night VFR requires normal VMC plus surface lighting or celestial lighting; i.e. the moon must be out.
The license to fly VFR and IFR is another issue.
