I actually did hit a cow on the road with my car, once, on a moonless night in the middle of Nevada, ninety miles from nowhere. I lived, my passenger fractured a rib, the jeep recovered, and the cow died; but in the sixteen years since, I can't say it had ever occurred to me that any person other than myself might have any liability for the damage.
Most bison in the USA are not wild game animals and have to follow the sames rules as any other ranch animal.