It's always been interesting to me that people in One Piece don't know world geography, or about Devil Fruits, and the exchange of technology is so limited. Some places have electricity and computers, some places are in the early stages of the industrial revolution, and there's no real mail or communication systems (denden mushi being another bit of technology that some people have and some don't.) Even in the pre-industrial world, you could send a letter from France to China.
The fact that information is so limited in the world of One Piece is one of those things that feels incredibly significant to me but doesn't get much time. I'm not sure if this is something the WG has orchestrated, or at least encouraged, or if it's just something they're happy to take advantage of.
I think of this so often when it comes to the crew. The WG is afraid of Robin, but maybe they should be equally afraid of Nami.