I've spent close to two full days trying to understand the nature of the infamous GPS shift in China. After sifting through the noise, two recurring symptoms are that:
- GPS coordinates (WGS-84) plot poorly on Chinese maps, with an offset ranging from 50 to 1000 meters.
- Google and Apple Maps in China have severe misalignment between their street maps and satellite imagery (live example)
- Cold War-era regulations mandated introducing random offsets into GPS chips due to security concerns
- protectionist measures aimed to favor GPS devices manufactured in China
- China simply uses a different projection system, and the offsets are not random
- GPS chips manufactured in China offset the coordinates they return, in order to match approved Chinese maps, which must follow the GCJ-02 datum
What is the actual story? This looks like the type of pervasive problem that merits a Wikipedia page, but I haven't been able to find anything authoritative yet.