This strict process is followed to protect the designation of origin rights so that when someone buys San Marzano Tomatoes they get what they expected. Similar to Champagne or Prosecco, it is about the region it comes from. DOP Denominazione D'origine Protetta meaning Protected Designation of Origin.
The D.O.P Certification to distinguish whether or not the "San Marzano Tomatoes" you are buying from your local store are truly authentic and from the precise region and the right strain of tomato, they are put through a rigorous certification process.