Why geolocation doesn't work in China, Mid-East, Israel, ..?


Hi I noticed that the geolocation aggregation doesn’t work for every countries or cities (API or Twitter Search)

Is possible to know why? Which rule? And a list where it is forbidden?

https://twitter.com/search?q=near%3A"hokkaido"%20within%3A15mi&src=typd (in Japan works)
https://twitter.com/search?src=typd&q=near%3A"Beijing"%20within%3A15mi (in China don’t works, You get irrilevant data)