OP, While I don't ride in the rain. In the major vein of your question, I do approach that stupidity in another way. While I have told my father for me personally, I refuse to be lit up like a blasted Christmas tree to satisfy his concerns and the dumb helmet rear light he bought me is a piece of junk because it can't be seen in the sun. When it comes to drivers' like the one you encountered, while I would stop them briefly to remind them that other motorists' may not be able to see them. So, Regardless of whether a cyclist can, or can't, see them which won't get them killed. They should think about the fact that, if another motorist doesn't see them for the exact same reason. There next stop won't be 'Home, Sweet, Home'. It will be a funeral home.