I started doing nights in Vietnam. Nap of the earth pilotage operations, all the way up to radar vectors to "targets" at IFR altitudes.
I started HEMS in 2001, in area that encompasses high cultural lighting urban areas, extensively forested no cultural lighting mountains, and everything in between.
We started operating aided in 2011. It is the single greatest enhancement to night operation safety.
My opinion- if an operator can't afford NVG, they can't afford night operations. My employer agrees, requiring management approval of each and every unaided night operation, and then- only in very, very favorable pre-defined circumstances.