The source of a 2013 outbreak of contaminated greens was purposely hidden from the public until after the greens were out of the distribution system. This was done to avoid discouraging people from eating ‘fresh vegetables’.
Once some time has passed, the specific sources of this contamination will also be revealed, even though they are known now.
Most recalls from the CDC/FDA are from products sold at least 4 months prior. That’s what I’ve casually noticed but ymmv. This one seems to be more timely.