The Chicago mayoral primary election is underway. They’ve winnowed the field a bit – down to seven challengers plus the incumbent, at this writing – and people are doing their polling, walking precincts, and putting up yard signs. And there are commercials; in the biggest media market in the Midwest, in which the Democratic mayoral primary is the biggest contest, you can already be sure that the only real winner in this election will be the radio and TV people, selling those 15, 30, and 60 second spots to put ads on the air. What are the issues? Tax and...