From 800ft at night, a low flat roof would easily be mistaken for a clear area. Flare and check height is equally difficult for an eol. You don't need to be that much in error to have a potentially fatal fall. All speculation from me, an ex police pilot with 7 years operating at night over a city. In my next 3 years flying an air ambulance I have discovered that minor bumps and falls can cause fatalities, life is so fickle, a simple wrong choice of seat in the bar decided people's fate.
This is a rumour network, some of us know 100% that certain contributors are talking real guff, however WE are speculating as well as them. More informed speculation, but still only opinion. Stop slagging people off for having an opinion. By all means correct errors.