My understanding from one of the articles was that McDonalds wanted them to make a special model that did away with some portion of the manual process in favor of press-button maintenance, and they did.
Unfortunately, it turns out that it's hard to replicate the reliability and adaptability of human manual labor mechanically sometimes.
The point is that McD-corp gets IceC-corp big money by mandating a single machine from them. IceM(achine)-corp do this through broken maintenance process. Hence IceM-corp see machines very often and ensures as a third party that food-safety of ice-cream produced by these machines is satisfied. This is what McD-corp is getting back from it. They don't trust die Franchises and let them pay money for their own inspection.
Unfortunately, it turns out that it's hard to replicate the reliability and adaptability of human manual labor mechanically sometimes.