Invasive species for one thing --- folks aren't nearly as careful about checking their vehicles as they ought to be.
Not huge enough when you're considering how the McDonald's have driven out little hole-in-the-wall places and that the presence of such a fast food restaurant requires a busy highway, or a reasonably dense population center.
Obviously you've never done trail maintenance --- an unused trail can quickly grow over, unless it is situated so that wildlife use it or there is some other mitigatingfactor.
https://www.bbc.com/news/world-us-canada-42104894
With more than 14,000 of them, it's not possible to be more than 115 or so miles from one:
https://www.rd.com/article/farthest-away-from-mcdonalds/