I think it's just that the geographical database used is less accurate for IPv6. Where just a country is known, it appears to use the centroid for the map (there is certainly not a great internetworking site in Alice Springs either!).

yes, it is like that. Hypothesis is that very inner core network routers lack accurate geo-location info, hence they are represented in the center of the country instead of in a city. This would explain the star-like pattern in every country.