Thais, in general, aren't into maps, and that includes local tuk tuk drivers. So, what is that map doing in the three-wheeler then? It's for foreigners. Notice that it's in English and that the various tourist landmarks are highlighted. The only time I've ever seen maps like this appear from the ceilings of tuk tuks is when drivers are showing travelers places where they want to take them. Just beware of those drivers who want to take you around the city for twenty baht. You'll end up at touristy gem and tailor shops rather than the places on the map that you intended to visit.