Twelve UK farms. Audited every three months by a third party we did not pick from a list of friendlies. We pay for the audits. We publish the result on the bag.
When a supplier slips the spec, we have a runbook. First, we pull the next batch. Second, we visit. Third, if the answer is not satisfactory, we drop the supplier and lose money for a quarter until we find another. We have done this twice. It is unpleasant.
We could have used a single trader, taken a 9% margin lift, and never visited a farm. We do not, because the QR on the bag would not say anything true if we did.