From the origin: Jim Munson on Coffee Co-ops
Co-ops are basically the same as mills--they "process" the coffee cherries (picked by thousands of farmer members and delivered by truck-owning and influential "collectors") from 35-40% moisture content "gata" into "asalan" green coffee (18% moisture) which is sent to Medan for final sorting and size grading (insane 15 hr drive in 15ton truck).
Farmers elect their Co-op delegates and collectors. In general I've been blown away by how seriously they take their responsibilities and by the overall integrity of the system. Independent auditors based in Jakarta review how premiums paid by importers are used. If a delegate abuses his/her authority the villagers don't reelect them.
We've visited Permata Gayo (very well equipped and probably the most modern), GLOC (young and vibrant), Tunis Indi (biggest), and APCO (very nice people). The few photos I've included here are from GLOC.
The local village co-op members can choose how they want to spend the premiums. Some build roads, waterworks, schools, others subsidize basic staples like rice and sugar. Still, these people are dirt poor. Some of my video interviews go into people's houses and show this clearly.
In short, buying FT certified coffees does seem to make a real difference but it's not nearly enough.