Cobblestone walls and fences don't use their full collision boxes when being moved by a piston

When cobblestone walls and fences are moved, they only have a 1 block tall collision box.

Looking at the first picture, we would expect the armor stand to get moved when the cobblestone wall is moved, since it has a 1.5 block tall collision box. What actually happens is the armor stand does not get moved and falls into the cobblestone wall when its collision box is set inside the armor stand.