It would be a different story if the cows broke through a fence alongside some local road or farm road and thence wandered on to the Interstate.
The reason for the fence maintenance requirements date back to the Eisenhower administration when the interstate system was first authorized for national defense purposes. High speed highways and critters, whether local livestock or wildlife, present a potentially lethal hazard to travelers. The fence is the last line of defense.
Anyone who has driven through the more desolate parts of I-80 in Wyoming and Nebraska will notice fences along most of the entire length save for a few sections where the terrain makes the erection of a fence nearly impossible. These areas, where there is a risk for wildlife, are marked with warning signs about wildlife crossing.
I live within 1 mile of US Hwy 95-A, which is in N Nevada. There are Open Range signs all along it.
Cattle aren’t the main problem here-—Wild Horses are.
Too many city people moving into this area & they just don’t get it.