This time 13 months ago, low-wage non-union workers had just mounted first-of-their kind strikes against the behemoths of the post-crash economy: fast food and Wal-Mart. One year later, we still don’t know how either effort will end. But their fortunes may have diverged. What had started with a walkout by a couple hundred fast food workers in a single city has spread to pull thousands off the job in a hundred municipalities this month. Those strikes reflect the theory behind several of 2013’s high-profile U.S. union-backed non-union organizing campaigns: that courageous and well-crafted strikes that don’t shut down a workplace,...