I strongly agree that these figures imply greater certainty about accidents that can be justified. In the end, each death is investigated by someone with a clipboard, asking questions, taking measurements and making judgements. They will probably try their best, but some of their information will be duff or incomplete.
As for wearing dark clothing at night, I would feel much more at risk without my hi-viz stuff and I am unable to understand others choosing to ride in dark clothing at night. Bike lights are not always great at helping drivers pick out cyclists, and a bit of reflective / hi-viz clothing does help. Like most of us I drive as well as cycle, so as a cyclist I look at other cyclists and note what makes them stand out for me when I am driving. Blinding rear lights, not helpful when you are trying to overtake safely. Weak rear lights, even worse. Reflective stuff that shows the body shape, great for judging position and distance, and very helpful for safe overtaking, or for abandoning an overtaking manoeuvre if the cyclist's right arm is raised to indicate a right turn. I know motorists should be looking where they are going and should try to see and respond to event the most camouflaged and unlit night cyclist, but if there is something I can reasonably do to make it less likely that a motorist will fail to see me I will do it. I have kids and they like to see their dad come home after a night ride.