The point is, they can only recall all the batches associated with the particular product name/producer they have discovered.  (I'm assuming that contamination is widespread across types of foodstuffs/producers.)  From the report, it seems China is the culprit (maybe other countries in the far east) because they have lax--or no--internal checks: if they have unhealthy practices across the board, the only effective result of sampling would be to ban all imports from there?

Don't fight forces, use them R. Buckminster Fuller.