Wendy’s, In-n-Out, Chick-Fil-A all use the same machine but no others have the problems McDonald's does.
It may appear that employees just don’t know how to fix it. But this is by design.
You see, the company that owns the ice cream machines (Taylor) earns 25% of all revenue through recurring repair and maintenance. They provide a lot of restaurants with machines but McDonald’s can provide the most revenue opportunity because of their market share, so some sort of deal was made between Taylor & McDonald's.
Instead of making readable error codes when machines break, they use complex codes so the employees have to call “the guy”, as referred to by franchise owners. If employees try to fix it themselves, all the directions in the owners manual end with “Call service technician”.
“The guy” is a Taylor repair man - who’s fees start at $144 for the first 30 minutes and $315 for every additional 15 min. Leaving franchise owners with expensive repair bills.
So a tech company, Kytch, created a piece of hardware to install in the machines to output legible error codes so the employees could fix the ice cream machine without using Taylor’s service.
McDonald's found out and banned them in restaurants and said they were working on a development of their own to replace Kytch.
Wild turn of events - this new development is being created by a company under the same parent company that owns Taylor. This new development doesn’t provide as good of results as Kytch does, meaning they’ll still have to call a Taylor repair man, maintaining the high percentage of recurring revenue. Kytch is planning to file a lawsuit against this Taylor sister-company.
So when McDonald’s doesn’t have ice cream, it’s because they don’t care about actually providing ice cream.
They've gotten to a point where they more care about whatever benefits or revenue share Taylor gives them for providing constant repair services (again, making up 25% of their whole business).
Sources:
The Real Reason McDonalds Ice Cream Machines Are Always Broken
They Hacked McDonald’s Ice Cream Machines—and Started a Cold War