Ummmm ... not that I know the exact legal structures, but P&O/DPW owns something that resembles "terminals" at least to the extent of having long term leases that support a capital investment in buildings and other infrastructure on land owned by local government entities.
Whoever is handling the containers is necessarily involved in unloading the ships. I'd say P&O/DPW is most directly involved in this regard.
But a segue here is timely, becuase P&O/DPW dosn't directly undertake the unloading and transfer activities. It has US subsidiaries, Joint ventures, and in short, a shitload of other company names come into play.
I wish I knew the details, I'd lay them out here. But looking at Miami as an example, there are enough players - it makes wrapping the mind around the deal more than easy.
Now, time for you to quote Sullivan, per your promise.
It's actually Sir William Shwenk Gilbert, whom I threatened you with ( and did post you some lyrics by, which you never commented upon and broke my heart ); not Sir Arthur! There no way ton post sheet music. :-)