I have to admit, that when I started cycling, I didnt know about the light thing. I bought a very cheap light to start with, when I realized I couldnt see at all on the mup without one, and figured that having a hard time seeing was just part of the bargain. I then found this website and started reading about cycling and quickly changed my mind. I stopped riding late until I made my own lights. Honestly, I think a lot of people just dont know how much danger they are in. Sadly, people often dont like to be told things and get defensive when it happens, so telling them could cause some problems. If you feel comfortable letting the person know how hard it is to see them, do it, but if they have an axe strapped to their back, I suggest passing quickly and letting them make their own way.