Yes, I have seen those. They are far from "maiming" it and barely pierce the flesh. Those barbed mini-spears are mainly to show the prowess of the matador, ie that he can get close without being hurt.
While it's true that bulls, like any prey animal, have a much higher pain tolerance than we do, the barbs have to penetrate the muscle or they wouldn't stay in, with the weight and drag of those pennants on it. They would make movement painful no matter who you ask.
