After years of trying to mine the wealthy around here, and instead hitting themselves in the face, the Seattle City Council has finally fixed on a potent way to tax the rich. Seattle’s latest corporate tax scheme will almost certainly run into some familiar obstacles, such as a skeptical mayor and a possible legal challenge from big business. But politically, this one is nothing like the failures of the past. It’s the work of Council member Teresa Mosqueda, and the premise is simple enough: Instead of tilting at windmills to try to tax wealth or high incomes, which is legally...