Wall Pallisade, fences and crenelated wall doesn't damage NPCs at all

Game mode: [Online]
Problem: [Bug]

[Free text]
Well, crenelated walls and fences normally suppose to damage only if you try to climb over them. And i think it should damage when you approach them. or at least if you try to attack those.
But wall palisade damages players when they get too close to those. However its does not damage NPCs at all. I just observed Purge NPCs attacking wall palisade in melee, and they just destroyed those, without taking a single point of damage.
What the purpose of those if they act just like a normal wall against Purge?

Steps on how to reproduce issue:

  1. Build palisade wall around your base
  2. Wait for the purge to happen (or use admin command to start it)
  3. Observe as NPCs attacking palisade and receiving absolutely no damage.