On one hand, this is a bunch of coordination problems, but on the other, it feels like a rational port acting alone could have said "We'll unload your ship only

On one hand, this is a bunch of coordination problems, but on the other, it feels like a rational port acting alone could have said "We'll unload your ship only if you let us load it back up with empties" rather than letting unloaded ships to zoom on back to China for the next load. Presumably there are complexities around this, but it sounds like they want ships to take back empties and the ships aren't because it's not worth the extra time and weight. A single actor, the port, should have the authority and incentive to demand it. Curious why that isn't the case.