As far as the open range laws, it ONLY applies in areas without fences. Like on OPEN RANGE If there is a fence, it's not open range, and the cattle owner is responsible for any damage caused by their property.
I've been around a couple of events of horses getting out of fenced areas in designated "open range", and the horse owners got to call their insurance agents to cover the damage to the cars.
That first part is definitely not true everywhere. It can very well be considered 'open' range even with fences along the road.
I doubt this bull was coming off of a public lands grazing allotment considering the time of year and place. That said, I bet there are cattle on public lands in Idaho everday of the year. Many desert/semi-desert areas are used as winter allotments.
