You may have noticed the highway signs, but not understood exactly what "Open Range" means for motorists. Open Range means livestock (cattle) have right-of-way over automobiles on public roadways. It means a black cow at midnight has a greater right to stand as an impassable obstacle in the middle of a desert highway than you do to drive down that road. That's right, if you plow into a 2000-pound bull on a public road, you (or your estate) owe the livestock owner for the lost bull. Nobody owes you for lost or damaged property, income, limb or life. People frequently die in collisions with open range livestock.
Urbanized counties in the West long ago rescinded their open range laws, but hundreds of thousands of square miles and thousands of miles of roads remain open range in the rural outback. In the open range, private property owners who do not wish to have another's livestock trespass onto their lands must build and maintain fences to keep livestock off their property. Ranchers are not responsible for building fences to enclose livestock inside their own pastures.
Ranchers vigorously defend open range as a tradition and a "right." Some are judicious enough to know not to collect on any livestock killed by cars, but others are not so tactful. Ranchers will not surrender their open range tradition easily and they oppose amending ordinances affecting open range. The current system is cheap (fencing costs thousands of dollars per mile), and has dividends of free time (no fences to maintain) and free forage for their livestock (the best forage on the range is often found on the narrow strips between roads and private or public fences).