In my area a lot of the lower income and day workers ride bikes for transportation, which is great, I think. However, as you discussed, many of them obviously never learned that bicycles are supposed to follow traffic laws, or for that matter, maybe they don't know the traffic laws. They ride more like pedestrians with wheels - going along sidewalks, facing traffic, no helmets, etc. Very dangerous, as you say, but I suppose I'm glad they're not behind the wheel of a car...