This is interesting. If Fedex charges more to send something with declared value above $1500 than if the declared value is less, then it ought to be providing something in return. It doesn't cost them more to deliver something just because it's worth more than $1500.
I am wondering if it's a question of wording. Reading Fedex's written words, it sounds like they are making sure they are not liable for consequential/remote damages (e.g., you ship something necessary for completing a contract with someone else, and because the delivery is messed up, you don't get the item and your contract is violated and your counterparty sues you for an amount that doesn't bear a real relationship to the declared value of the shipped item). I can see why Fedex would want their maximum liability to be the declared value of the item shipped. They say they don't provide insurance of any kind, which I think protects them in this consequential damage situation. What isn't clear to me is that they are saying they are not liable for anything above $1500. If that is the case, then why ask you for the declared value and let you state it's above $1500 and charge you more for it at all?
They say the shipper has to prove the actual loss. If the declared value is X (and it's above $1500) and the item gets lost, that is pretty obvious that X is the actual loss (not consequential loss like the example I gave above). The fact that Fedex insists on opening the package to inspect it would seem to support that they do make sure the item is as declared.
I would love to know if anyone has actually shipped something, declared it above $1500, paid Fedex's extra charge for shipping something worth more than $1500, lost it during Fedex's shipment, and then been denied any compensation by Fedex above $1500 with Fedex invoking this language in their contract.