Commentary From Christmas toys to clothing and auto parts, shortages of imported products are forcing factories to idle, store shelves to sit empty, and consumers to panic. What else is in short supply? The truth about what’s causing this economic crisis. President Joe Biden, who brags about running “the most pro-union administration in history,” won’t admit that longshoremen’s unions are holding the nation hostage, refusing to allow the use of automated equipment to unload container ships and get the goods onto trucks faster. The United States is the world’s largest importer, but its major ports at Los Angeles and Long Beach, California, rank a dismal 328 and 333, respectively, in the World Bank’s Container Port Performance Index. That means nightmare inefficiency worse than most developing countries. Not one U.S. port made it into the top 50 for speed and efficiency. In contrast, Japan’s Yokohama port ranks No. 1. Nearly 100 …