McDonalds Monopoly not only causes problems for tourists, and even the people who live wherever.
McDonalds, among other things, is the world's largest purchaser of potatoes--for its "French fries", of course. Now these particular potatoes have to be long and thinish, to fit their machines. It's only reasonable--conform the natural to fit the technological.
Now only a particular potato works in their machine--a Simplot, an American potato, of course.
Now, the impact of this monopoly is quite simple. There is greater demand for this variety of potato than for any other. As McDonalds spreads over the world, it supplants local diversity, not only of the cuisine, but also of the local potato. If the largest buyer of potatoes will not buy what you used to grow locally, you'll import the seed of what they will.
McDonalds will only buy the potato that will fit its technology. And why not? They've invested enough capital in it, and want a reasonable rate of return from it.
And maybe, the loss of this particular biodiversity is unimportant. But I think not, monoculture is not to my mind desirable.
There's also a metaphor here for the effects of monopoly, and it's usual technology on us, and on the world that may not soon be able to sustain us all.