Lili's safety-minded thought for the day

It seems like half of the Australian workforce wears high-viz gear on the job, and it is generally accepted that high visibility clothing is a necessity for safety in many work situations and is generally a good idea that is cheap and easy to implement. I've even seen a bright pink high-viz waistcoat being worn by a lady doing some work. The popularity of high-viz has influenced fashion in Australia, with day-glow orange and yellow featuring in garments and high-heel shoes for young women and girls in the last few years, so why oh why don't cyclists wear high-vis or bright colours when they are riding on the roads? Are there day-glow coloured orange, yellow, pink or green bicycle or motor-bike helmets on the market? If there are, why don't all cyclists and motorcyclists wear them, for safety's sake, for their own sake?