I'm not trying to write off the physics system as being perfect, nor am I a dev on this project. I can understand your sarcasm in my "explanations about bending walls and such" but I am just trying to explain why you're seeing what you're seeing. All feedback received by the community is being passed on to the development team for episode 2 and all future episodes, so your feedback is certainly heard. I have compiled two videos of myself in the same area stacking items.
*NOTE* Yes, my framerate is terrible in these videos. There are several reasons for that.
Here is a video of stacking items vertically (which I never do when I'm playing -- this is just for example). There are many ways to stack items vertically, this is just one.
Here is a video of stacking the second trash can horizontally, which is actually the method I use to reach high levels when I'm testing the game.