In the US, the entity that collects the blood can have a lot of requirements to notify the donor about and report infectious disease, so they are required to maintain records about the donors. They also generally happen to be the entity that distributes the blood.

I would guess that the implementation has the hospital passing a list of numbers read from barcodes to the blood center and then the center either sending the messages or passing phone numbers to the county council mentioned in the article.

I think I agree with your reaction though.