rust said:As has been mentioned, if you want to transport cargo
over a long distance by plane, you use a truck to deliver the cargo to the plane and another truck to distribute the cargo once the plane has landed, but
it would be a somewhat bizarre idea to transport the truck on the plane, too.
Correct, because planes can not go everywhere a truck can. A more accurate modern day depiction of what this is, would be using one plane to deliver the cargo to the bigger plane, then the bigger plane delivering the cargo to a smaller plane at its destination, with no trucks at all.
Since spacecraft can go everywhere, however, there is no actual need to transfer the cargo. Which also means there is less chance said cargo could be damaged or lost because of sloppy handling while transferring it from ship to ship.