That they can't adjust because of the different area (the buildings, the crowds) is true, though it would work the same for those who grew up in a city. They won't adjust because there aren't any buildings, or crowds. Those who grew up in a city are also relying more on other people, or machines for that matter. In a way, I admire those who dare to take things on their own, not relying on others.
I do not believe it's true that they are scared easier though. I think it would be the exact opposite of it, actually.
Despite me grewing up in a city, I am afraid of heights and I do not enjoy crowds.