Then why do the rodents only eat wires on new vehicles? This is a recent phenomenon, like within the last ~15yr of vehicle manufacturing. Cars and equipment older than that don't get their wires chewed up.
Source: talking to auto mechanics and people who operate fleets of construction equipment.
Rodents have been eating the wires of cars forever. This is not a recent phenomenon. All of my 6 cars range from 1980-2000 and most of them have had an infestation at one point or another and I have repaired chewed wires in a couple of them. I've heard soooooo many stories from old people of mice getting into cars and eating wiring, it's been a problem since we've had cars.
Source: talking to auto mechanics and people who operate fleets of construction equipment.