And labor sets idle without raw materials, components, and goods.
All of which are delivered by truck. Think of your car, it's made of thousands of individual parts, all of which were dlivered to the car plant that produced it by truck. In turn your car was shipped via truck to the dealership you bought it from. Now multiply this by everything in your house.....including your house. Cheap fuel means cheaper prices for all; manufacturers, farmers, retailers, and consumers.