Maris, I believe it was a combination of cost and dwindling professional usage of colour negative material. The amateur market, which was huge compared to the professional market, even though it was basically all 35mm format, was very price sensitive.
Fuji had older 3 layer colour negative material for quite a lower price, which is what supermarkets and chain stores sold by the bucketload.
Kodak Ektar 25 Professional, was my personal all time favourite colour negative film for saturation of colours and clarity; as in, virtually no visible grain.
Once Fuji Reala turned up, I switched to that and never looked back. Sodium lighting of some industrial machinery subjects I did, were simply stunning in comparison to any other film.
I did all of my own Kodak Color Print Film for clients as it was the only way to control the colour correctness in the 4x5" transparencies that I supplied. The snap of those really correct looking colour colour print films on a light box, was something else. I miss that film. I still have a couple of boxes in my refrigerator, but I doubt they would be that great these days.
Kodak Color Print Film was three layers of emulsion, with each layer of emulsion being three layers for a total of twelve layers. But I'm not 100% certain of that, my memory is fading a bit.
With regard to using B&W film on the coloured cliff faces, I used colour negative material in 1984 when I rode my heavily laden motorcycle along the beach to the ship. On an earlier trip in 1980 to Cape York to see the tip, I used B&W film for the coloured cliff faces. Upon showing some B&W prints to friends, I also received a ribbing.
