re: limited liability clause
The primary obligation of the courier is to deliver the package from point A to point B. If the courier is guilty of fraud or negligence in the performance of this obligation, the injured party is generally entitled to damages as a matter of right. But the right to recovery may be limited by contractual stipulation such as by way of adhesion contracts, or "the fine print" prepared solely by the courier service and without consent to which the service will not be performed.
Adhesion contracts are perfectly legal and binding. Yet they are strictly construed against the party that drafted them, and may well be struck down if established to be one-sided. I think it is important to examine the purpose of the stipulation requiring the declaration of value. If it is required mainly so that if the value is expensive, the employees of the courier are put on guard to take care of the package. However, the courier is obligated to ensure the well-being and safe delivery of the package no matter the value, so on that ground alone, I think the injured party should be able to recover beyond the stipulated limitation. Also, if it can be established that despite the stipulation, employees of the courier actually told the shipper that it is not necessary to make a declaration (as has happened in my case), then I don't think the limitation should operate.
It might be a different case though if for example, the declaration is necessary in order to trigger an insurance agreement with a third party who may have agreed to insure packages worth a certain value, or wherein the declaration is necessary in order to make operative some legal protection against either the shipper or the courier.