Historians of technology have generally credited the standardization of shipping containers in the mid-twentieth century with transforming global trade, since a uniform container size allowed cargo to move between ship, rail, and truck without repeated unloading and reloading, sharply lowering the labor cost and transit time of moving goods across long distances. This account typically treats containerization as a primarily technical achievement: an engineering solution to the inefficiency of loose cargo handling. A revisionist strand of scholarship argues that the technical innovation was, in fact, the easier half of the problem. Container-compatible cranes, ships, and truck chassis had been proposed, and in some cases built, well before standardization achieved widespread adoption; the harder obstacle, these historians contend, was institutional. Ports were governed by longshoremen's unions whose labor contracts, seniority structures, and hiring-hall practices had developed around the handling of loose, irregular cargo, and containerization threatened to eliminate the great majority of dockworker jobs at any port that adopted it. Shipping lines, for their part, had sunk enormous capital into break-bulk vessels and were reluctant to write off that investment for an unproven format. On this account, standardization spread only where a critical mass of ports, carriers, and unions simultaneously renegotiated their arrangements, a coordination problem far more intractable than the engineering of the boxes themselves. A further piece of evidence cited for the institutional account is the uneven pace of adoption: ports with comparable cargo volumes and nearly identical technical capacity to containerize nonetheless converted years, and in some cases decades, apart, a pattern the purely technical narrative does not by itself explain, since the engineering solution was, after early standardization efforts, equally available to all of them. Which of the following, if true, would most strengthen the institutional account's explanation for the uneven pace of adoption described in the third paragraph?