When encountering a public problem, people tend to fall into one of two camps: one camp, the larger one, says, "There oughta be a law." The other one asks, "How has the government created or aggravated the situation?" We know which camp Maestro Trump belongs to. Take prescription-drug prices. Because Americans pay higher prices on average for prescription drugs under patent (but not for generics) than people in other countries pay, Trump, who used to call price controls "socialist," has ordered the drug companies "to offer American consumers the most-favored-[developed-]nation lowest price."...