I don't understand the problem and, seemingly, the outrage in some of the replies. If it is dark and there's traffic it is safer and useful for everyone to be

I don't understand the problem and, seemingly, the outrage in some of the replies. If it is dark and there's traffic it is safer and useful for everyone to be visible. Obviously this depends on how well the streets are lit, if they are very well lit it may not be a big issue. As a pedestrian at night (which is pretty much any commute to/from work in winter in the UK) I know that sometimes cars don't see me or see me at the last moment if I wear dark clothes, or even any clothes that are not high-viz. And as a driver I know that this is because pedestrians, or even cyclists at crossings, can be very difficult to see in low light conditions (good forbid there's fog as well!) even if you're driving carefully. This is all common sense, really. In my neighbourhood, which is residential and poorly lit as many are here in the UK, people also wear lights on themselves when they walk their dogs in the evening, and they usually also make the dogs wear lights. When I go running in the evening I wear a high-viz jacket and one of those chest lights so that I can be seen and can see the potholes as well. Again, common sense for safety in such conditions.