“All I am saying is that there is no way for the publisher to know if the ink is or isn’t soy or vegetable based. The only one who knows is the manufacturer and the publisher doesn’t buy it directly from them.”
Printers and newspaper publishers, like other businesses, list requirements for products they purchase. If they require soy-based ink and a manufacturer lies and sells them petroleum-based ink, the manufacturer can get sued. Also, it seems that soy-based inks are cheaper. So why would a manufacturer risk a lawsuit and his reputation so he could make less money?
If the New York Times (for example) doesn’t buy their tankers full of ink directly from the ink manufacturer, whom do they buy from? Staples?