Bottom line is, if Apple provided the return label, then they are responsible for making the claim with UPS and the OP has nothing to do with it. Otherwise, If OP created the shipment then he is responsible for making the claim with UPS
Correct, the right to claim goes with the contract for carriage - in fact it is probably part of the UPS terms. In most legal systems the only persons with the right to claim are the parties to the contract. In this case the contract is between UPS and either Apple or the OP depending who ordered the job, and third parties including the other of (Apple and OP) are likely to have no rights whatsoever.
What you do find often though is manufacturers understating the value of the goods being returned to them in order to avoid potential duties or even to tweak the numbers on the books.
Now that would be fraud, or maybe false accounting. However, it could be argued that the value of a failed phone is its scrap and recycling value so $50 might be reasonable by this measure. However that also raises the argument that if Apple declared the value of the consignment as $n, then $n is all they can ethically - and probably legally - bill to the sender if by some anomaly they can't claim against UPS. They have freely declared that to be the value of the lost consignment so that is pretty strong evidence of their "loss".