I'm pretty sure that ice cream is a high margin product like drinks and McDonald's has found an indirect way to extract most of the margins. The problem is that

I'm pretty sure that ice cream is a high margin product like drinks and McDonald's has found an indirect way to extract most of the margins. The problem is that the technician service fees are a fixed cost designed to be revenue maximizing for the average restaurant. Franchises selling enough ice cream to pay the fixed costs stay in the game, the ones who don't simply keep them out of order. This is effectively a price discrimination strategy. By making the machine mandatory, they can offer the menu item in every restaurant, but they only have to collect money in proportion of ice cream revenue.