What's the point of Postcodes?

From today's NZ Herald Sideswipe column:

NZ Post has just launched its "what's your postcode?" campaign to remind people about using postcodes, writes Paul. "My wife went to post a parcel at the Victoria St post office in Auckland's CBD and although the parcel was correctly addressed including the postcode, for Kaiwaka in Northland, the staff at the counter were unable to locate the code on their system and consequently informed her that they couldn't accept the parcel!"

The 'Paul' in this item is me. When Rochelle related the story to me, I got on the NZ Post website and used their postcode finder to look up the code she'd used in the address. It came up instantly with the correct details. I've no idea why the staff at the post office were incapable of doing this. Coincidentally, the glossy brochure from NZ Post promoting the Postcode education campaign arrived in our mail box on the very same day that this incident occurred!