I think you're right, Super... Now I see it won't be easy to install a coupler there. Perhaps they made universal mold for motor cars and trailers. The train in that video is solo railcar, but red Bantan Line train and one of older Kitaro trains are three car combinations, and they needed the front hooks on trailers. On the newer Kiha trains (new Kitaro/Medama trains) there is no front slot on motor cars.
My YouTube Channel: Mister No