Ah, but you could do that with a golf-cart with a small diesel. You can tow any load with any size of engine, with the right gearbox.
(If you can put up with crawling at a walking pace going up hill...
)
It's a conundrum, and a bigger conundrum that people who just need a vehicle good for one (bicycle/motorcycle), people who need vehicles good for two people or one and a lot of groceries (small car), people who need vehicles to carry several passengers (minivans), people who need big trucks for work (SUVs/pickups) and people who need to deliver ten tons or more of goods (big rigs) all have to share the same road.