That had more or less been the explanation in the books for decades, and even in George Lucas' notes from 1977: > It's a very simple ship, very economical ship

That had more or less been the explanation in the books for decades, and even in George Lucas' notes from 1977: > It's a very simple ship, very economical ship, although the modifications he made to it are rather extensive – mostly to the navigation system to get through hyperspace in the shortest possible distance (parsecs).