Because most coffee is not tested for what is most likely to be in it. Ochratoxin A and aflatoxins. By-products of the moulds that grow on green coffee during transit and storage. Small amounts are common. Most roasters do not measure.
We test every batch at an independent, ISO 17025-accredited laboratory and print the result on the bag. If a batch fails, it is composted. Not re-tested. Not blended into a larger lot. Composted.