RichieRich .... I am under the impression you don't actually know what you are talking about -- on this point.

I do actually work in the industry. Containers are locked with "rated" twistlocks to each other and the deck of the ship and then lashed with turnbuckles and rigid rods to the deck. DEFINITELY not loose as you stated.
I HAVE seen vessels arrive in port with mangled and twisted containers (also gaps where they have been smashed overboard) by heavy seas in the Bight.A winter storm -- not a cyclone. So yes they do go overboard, albeit not nearly as many times as I stuff up a gybe and you imply.
I understand the upset an event like this causes and I too am pi__ed off about it but uninformed comments like yours do not help the situation. You obviously live in Queensland and probably enjoy the benefits of a lifestyle built on an economy sustained by exports of mined products and imported boards and sails and X-Boxes. Do they arrive with Santa? - I don't think so. My kids think they do. They actually come by ship. Ships are actually quite necessary I think and a lot less polluting (usually) than trucks and planes.
This tragedy may well be caused by human error and lack of judgment but please stick to facts 'cos an Australian shipping industry is better than a foreign "flag of convenience" shipping industry, which is better than trucks on the road etc etc etc.
The whole system of pollution control seems to have had a meltdown because to have the incident happen in the first place is most likely bad fortune or maybe stupidity but to then pollute the Brissie River has got to be an absolute clusterf_ck of monumental proportions.
It's probably a good time to pressure the government to beef up the pollution response methods while the election is happening and try and protect what is one of Ozzes great coastline regions.
Off my soapbox now.

Good luck.....