Granted but somebody some day would show up with unfriendly intentions...
That may well be the case, but ask yourself this question:
If I were in a world where fresh water, plentiful food, and medical care were a luxury, how would I behave when I came upon a community where all three were available?
Would I just try to take what I wanted and hope that there were no non-Amish in the place who would have no problem shooting me? Or would I try to find a way to have them take me in?