People just assume if you can walk up to a wild animal, it's tame.
To a bison, killing a human is like swatting a fly. Well, easier than swatting a fly. We're a bigger target
We're not a threat, we're not food, we're just a potential annoyance. Dumb enough to get close to a calf, and then you're really fucked. It's like picking a bare knuckle fight with a wrecking ball.