"Yet when even a third-world flag of convenience shipping line goes bust the ship can be impounded until the crew are paid."
Under maritime law crew, if unpaid, can have a lien imposed upon the ship (writ "nailed" to the mast) until they receive their wages. However if they leave the ship and return home they would lose their right. Can take months to sort out. Would you want to stay aboard your plane until all is sorted, or would you be better off getting out and finding a job elsewhere asap? Recently a case in UK were a crew (Indian I think) remained on board for over 12 months. First time the ship went up for auction not enough money raised so more delay until a buyer appeared.