… is from pages 544-545 of Douglas Irwin’s superb essay “Adam Smith and Free Trade,” which is chapter 32 in the 2016 volume, edited by Ryan Patrick Hanley, Adam Smith: His Life, Thought, and Legacy :
At the same time, Smith generally believed that direct interference in markets by government was unlikely to work out well. There were two reasons for this skepticism. First, government tended to be much less responsive to the needs of the people than self-interested merchants; merchants had more of an incentive (and more information) to attend to the desires of their customers. Second, special interest groups could manipulate governments, leading to policies for their own enrichment rather than the public benefit.