Example where I need this:
To make lamps that can be placed on a path and are walkable, or simple entities that are used as ground decorations with an animation. There are some hacky solution with setting the collision_box in weird ways, but this will just create other issues that are then open to the player to avoid.
This is an example with an already "hacky" 9x1 collision_box
![Image](https://forums.factorio.com/images/ext/df3d3a5291df9135110320fbc4beb8e1.png)
![Image](https://forums.factorio.com/images/ext/f252d3ea58e6f5521bcfe1c924c722da.png)