Why do ships do this?

They do it because it's cheaper than doing it properly in port.

And of course nobody who could stop them cares enough to bother!

Why would anyone want to dump palm oil in the sea ? Surely it is a comodity that gets transported from A to B and is not a waste product

They may have been flushing out their tanks. To do that in port costs a lot of money but sea water is free and they don't have to pay for it to be taken aways and disposed of properly.

Not a very good thread title was it?

j07 It's not that it's "not a very good thread title", it's that it's difficult to know what to say other than vampirequeen's replies. I am sure that many people are distressed by the sight of these poor guillemots, especially as the rescuers are having a problem finding the best way to clean them up.

I am afraid the answer to your question comes down to money, selfishness and greed, as it so does to so many questions.