I believe it's called return fraud because the perpetrator orders and receives an expensive item, opens it and substitutes another item of similar weight, reseals the box, returns it for a refund, and the retailer returns the item to stock because it appears unopened.
The same thing happens with "parts" that are part of an item purchased that can't be purchased by itself. So, of course the perpetrator buys the entire item only to remove the special part and return the entire package.