I remember reading some time ago that the basil leaves in canned San Marzano tomatoes are not for flavor or similar purposes. After all, how much flavor can two shriveled leafs of basil provide in a can that is 28 ounces or more. My recollection is that there were tariff reasons for the basil. It took me a while to research this matter but I found this at Chowhound: http://chowhound.chow.com/topics/551713
. If the Chowhound explanation is correct, then it appears that adding basil leafs to the San Marzano tomatoes makes the combination a "sauce", or something similar, and that may mean lower tariffs.