It could be combination of relaxed grading standards or better quality coins exist in china, less handling for sure compared to coin that was shipped to the US, carried to shows, mailed to customers, etc, while the mainland coins sit at store or safe until someone buy them.
For me NGC grading as really tightened up in the last two years, last batch of 27 coins only 1 MS70, previous batch of 36 only 1 also. This weekend I bought a nice collection of 1994-1999 key fractionals from original owner, hoping these will earn some MS70s.