It’s so much worse than you realize. All blood and plasma must be obtained by “donation” for obvious ethical reasons, but American prisoners get incentives for participation/punishment for non-participation. Private American medical companies make billions of dollars in profit every year selling blood on the international market, but the prisoners don’t see a dime of it. The sellers are so unscrupulous that they have been caught knowingly selling tainted prisoner blood, and continuing to do so after being caught.