Two quotes if arguments about postcodes don’t make you fall asleep.
An Post, Ireland’s main, state-owned postal service: An Post does not support the introduction of a public postcode in Ireland. It argues that it already operates a state of the art postcode, that it would not be viable because of the non-unique address outside Dublin, that compliance would be a major problem and that it would not improve quality. (Comreg 03/50, page 42)
Universal Postal Union (International, UN-backed organization for postal services): The postcode is the fundamental, essential element of an address.
A unique, universal identifier, it unambiguously identifies the addressee’s locality and assists in the transmission and sorting of mail items. (UPU)
I first saw the UPU quotation on someone else’s website, but I’ve lost the reference.