I've traveled pretty extensively across the world for work and very few places have an internet connection that compares to even a modest broadband connection in the US. Not only that, I deal with this problem weekly from our partners in 75 countries across the world who don't have good internet connections. As well, you're discounting the world's oceans. I've worked on a ship where we provided an extremely limited internet connection that would not be suitable for rapid development work.

I'd say it's a pretty small portion of the planet that has a decent internet connection, but the detail is how you define "decent".