Prior to 2012 in the UK all night flying was subject to IFR but then the regulations were changed following an EASA directive and night VFR flying has been permitted. Whilst the requirement includes "to be in sight of the surface" just what this means at night is hard to really define. Does it mean beneath you, or anywhere you can see something fixed - usually lights? And that can change quickly, with weather you can't often see, particularly as ground illumination becomes scanty. So night flying has plenty of scope for trouble when permitted under VFR.