Yep Places like McCain foods do this on an industrial scale that brings the cost so far down that even McDonalds wouldn't be able to compete with. They're still likely going to be doing so much business that they'll be getting a favorable contract for it but it'd still be silly to build out all of that themselves.
This may be inaccurate now - but a few years ago I stopped at Idahos potato museum. If I remember correctly - the McDonald’s fries are actually a product of a lot of food scientists hard work. There are multiple types of potatoes involved that are turned in to potato product. Those are then mixed together in a specific ratio before they are reconstituted into fry shape. I think even the combination of oils and temperatures are very specific to McDonald’s.
No, they're mostly just cut potatoes. They get a coating with some stuff in it you wouldn't find on homemade fries, and the cooking is of course quite standardized. But nothing like mixing multiple varieties of potato and reshaping them as fries.
