Why don't all Walls have a second creature type that represents what they are made of?

For example, Wall of Blossoms is a Plant

Wall of Bone is a Skeleton

But why isn't Wall of Fire an Elemental?

Or why isn't Wall of Junk a Construct?

I think because Elemental is more than just "made of fire", there needs to be some sort of being to be an Elemental. Otherwise, Shard Volley or Stomping Slabs could also be Elemental because they're made of rocks. Compare with Vent Sentinel or Plumeveil which are actual living Elementals.

A pile of machinery, similarly, is not a Construct.

This bothers me less than the zombie inconsistency. Everything else that does and came back a zombie retains the type it was before it became a zombie. But for some reason, humans don’t. Zombies that clearly were humans - are no longer humans once they’re zombies.

Walls always existed in a weird place for me anyway. For a lot of creatures, it had two types - its race and its occupation. Elf scout. Human advisor. Naga wizard.

But what is a wall? Is that an occupation? If it’s non living... does it even need to have a race? A wall of stone is just that - rocks arranged to perform the ‘occupation’ of being a wall.