The "scary bit" problem is something that I noticed the first day of trail riding when I was a scout; I think it was a bit of black plastic trashbag that blew up right in front of us that spooked first my horse and then two other horses that were behind me when they came up onto it. Although I've not ridden a lot in the years since then I suppose that it has something to do with the way the horse sees the world. Do they not have binocular vision like we do? I don't know; not every horse spooked, I suppose some of them were used to such things or just didn't notice it when it was chattering about in the wind!