That is the third leg of the three processes to eliminate rodents. Sanitation, which I covered, exclusion, which is a Fort Knox coop, and elimination, the traps and poisons.
The reason that process is last is because if you did clean out a population a new batch would immediately move into the territory. Nearly all wild animals and vermin stake out a territory and have to fight to protect that territory from encroachment. Momma has babies and the babies themselves will be driven out once they are mature because the territory has a finite amount of food available in a natural situation. Those young rodents have to find their own territory that will support them or more likely, fight for a territory and drive out the current occupants.
Where humans cause problems is when we provide unlimited amount of food which causes the vermin or prey animals population to explode to the point that natural predators can not keep the population in check.
So removing the food forces them to move on or die of starvation. If you don't it is a matter of time before they find your vehicles and begin eating the wiring.