For cars, it mostly boils down to people's disgust at the mere thought of being even momentarily mildly inconvenienced by someone going slower than they want to

For cars, it mostly boils down to people's disgust at the mere thought of being even momentarily mildly inconvenienced by someone going slower than they want to go. For pedestrians... Some people seem to feel threatened or indignant when they can detect that someone is going faster than them. Anyone going slower than me is an idiot and anyone going faster is an asshole.