I don't know if anything can be done about it but as an observation, caltrops doesn't stop anyone that is using pathfinding. Click the other side of it and you just automatically navigate through it. NPCs do this as well. It could be the single case where pathfinding just... works.
Also, when you destroy the caltrops they have a chance to drop loot. Seems exploitable :0
Edit: You also get xp.
Caltrops
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