Maybe it's just me, but I can't find a purpose for these transportation containers, such as the wheelbarrow, cart, and trader cart. Aside for the trader cart, they can't even carry the basic ground materials that you'd expect them to carry. Meanwhile the traders cart is too slow to even bother with since it's more practical just carrying these resources in your pocket. While it would be great for animals to help us transport these containers more efficiently, I don't see why it's more efficient to put these resources in my pocket than in my transportation containers as I move them. It's completely counteractive.
These items were invented to make things easier for mankind, not more difficult. These transportation containers are nothing more than stationary containers, because that's mostly how they're used unless the person doesn't know what it's just more efficient putting these resources in your pocket. I believe this is a real problem in the game, making things more difficult than they should be for absolutely no reason. It's impractical, user unfriendly, and historically inaccurate.