Economist: WHEN John McCain laid out his plans for reducing America’s dependence on oil to an audience in California on June 23rd, the candidate’s keenest listeners were 6,000 miles away in São Paulo. Mr McCain argued that the tariff on imported ethanol of 54 cents per gallon should be scrapped. Others in the Senate (though not Barack Obama) are pushing for it to be reduced. Either way, the case against the tariff has been strengthened by high oil prices and by the June floods that damaged the …