The Greek Coast Guard and the US Coast Guard are not run by the same people. If the Greek Coast Guard didn't ask for international help in Greek coastal waters, it won't come.

Shipping is and has been Greece's most important industry since Ancient times. They own more merchant ships than any other country. The Greeks know their way around boats. Some criminals using shoody equipment and not following any safety procedures broke the law on the ocean and it killed a lot of people who had paid them money to move them into another country illegally.