Even if you are in a car you are not safe. A bison can easily flip a car. It can get up to 30 miles per hour very quickly. And its horns and very strong neck muscles are its main weapon. Nobody should be this close to a bison. In fact I am not sure how close you can safely get. Ranchers who raise bison are injured all the time.
I have no problem standing next to a bison. As long as he is hanging upside down while I was skinning him.