I don't know why this would surprise you. People drive like this all the time. Happens to me whether I am riding my bike or driving my truck. My philosophy about driving is always be defensive and expect people to do something stupid. They are too busy eating, talking on their phones, texting, changing radio dials, etc. to pay attention to driving. Or they just go without looking and assume everyone will get out of their way. When I'm driving, I blow my horn at people like that. A little negative reinforcement might at least make them pay attention for a few minutes.