I think the manufacturer doesn't trust us to use an accurate fuel guage so they add a safety cushion to protect us. I guess they figure we can run backhoes, log splitters, front loaders and grapples, but those gas guages can be really tricky. It's like those spring loaded sink faucets at the airport that give you one teaspoon of water before they shut off. Can't trust travelers with something as sophisticated as a real faucet with a handle.