> Why don't you have enough trucks?

This is addressed later in the thread. Normally, many trucks haul containers to their destination, unload the container, then return it empty to the port, pull it off the trailer, and haul away another loaded container. But the port is too full to accept empty containers, and zoning laws mean truck companies have already maxed out their own container holding areas. This leaves enormous numbers of truck trailers sitting idle, waiting for somewhere to put the empties they're holding before they can pick up more goods to haul.