Bulk transportation of goods is the most economical way of moving items. A single ship load of bananas is less expensive to move than using a dozen smaller ships. We see this all around us. Oil and gas comes to the UK in vast ships and is distributed in large road tankers and huge pipelines - and in the early 1900's London used to get milk brought all the way from Devon and Cornwall by trains belching out thick black coal smoke. Customers want products from around the world (how else do you get fresh fruit and vegetables in December? ) and food can't move all by itself!