I stopped into Photo Warehouse, a good-sized shop on the Great North Road that still carries film and darkroom supplies. They only stock Ilford chemistry.
I asked about Tri-x and was told "they don't make it any more." When I said that I was pretty sure that wasn't true, I was told, "well, that's what the distributor tells us."
So now I have a conspiracy theory: maybe there are two distributors of film supplies in the Auckland area? One makes a little more margin on Ilford and Fuji, so is discouraging use of Kodak products.