Seems like more of a tragedy of the commons, with each ship (A) assuming it's fine to leave empty because some other ship (B) will grab the empty containers. That's all well and good until (A) comes back, and then it sits there waiting like everyone else.
Going back empty works once. Or more times if you're headed to a different market, I suppose.
I believe that's not the price for the physical box but rather "a container's worth of shipping". Empty containers are probably going up in price a lot now too - I don't really see why Ryan thinks there needs to be military intervention here. A shortage of empties in China and a surplus in the USA will get resolved real quick by people on the ground (=within the latencies afforded by the slow speed of ships themselves) as there's money to be made there.
Going back empty works once. Or more times if you're headed to a different market, I suppose.