Well Pete, if you look like your avatar, even I would be scared of a large blue man with a huge chin and a topknot riding down the street!
The answer is crystal clear to me... people are simply not paying attention to their surroundings. They're too invloved in their own worlds to look around them and see what is there. I mean, when you have the windows rolled up, A/C and radio blasting on your way to get a triple greaseburger Mega meal from McD's, how can one be expected to look for someone else on the road!
I scare people sometimes even long after I announce myself, so don't feel like it's just you.