Generations of Popes and Kings and Presidents have known this about human nature: when people really want something, they're willing to pay for it. Which is why taxes on alcohol and tobacco have long been a reliable way to fill government coffers.
But in recent years, health officials have turned to the tariff system to curb public consumption of fat, sugar, salt and more. With the obesity epidemic now claiming 34% of U.S. adults, legislators are proposing taxes on the added sugar in products like sodas and the salt in snack foods like potato chips in the hopes that higher costs...