Now, regarding sheet films.
The bulk of Kodak film is coated on 5 mil or thinner support. This is for the Motion Picture, 35mm and 120 markets. The 4x5 film is on special order 7 mil support. This is what drives up the costs, as I suspect that Ilford's product mix is more even and thus can be costed out more evenly.
There are other factors in this as well such as the very low demand for sheet film (which may rise as more people dig out their LF cameras and make plates).
BUT, remember again that there are about 70,000 members here, but only a small fraction ever post or even use film. I would estimate about 10 - 20% actually use film, or perhaps less. And that usage cannot support three volume manufacturers.
As for business models, for those who missed this, in 2005, when Ilford faltered, Agfa failed and EK left the paper busienss, the models said there would be a 35% drop in film sales in 1 year. Well, that took place in 1 quarter and did a LOT of damage to all of the companies making film and paper. And look! Where is EFKE today? It was ideally suited to small custom runs, but could not make a profit, not even enough to keep the machines running or the buildings in suitable repair.
PE