The visible cost: the refund
The refunded sale removes revenue, but that is only the first impact.
The logistics cost
Pickup or return shipping adds another cost.
The inventory decision
A returned unit may be resellable, discounted or unsellable.
The marketing cost
Customer acquisition spend is not automatically recovered when the order is returned.
Distinguish return rate from return cost
Two products can have the same return rate but very different financial impact depending on shipping, product value, resale condition and acquisition cost.
Connect return reasons to action
Reason codes should support decisions: sizing issues may require merchandising changes, damage may indicate packing problems, and repeated customer rejection may require confirmation or targeting changes.
Every event should remain connected to the product, contact or transaction that created it. That is what lets ERP explain a number instead of only displaying it.