The Corleones were Sicilian.
They probably were used to low quality tomatoes. You might have to ad a dab of sugar to common tomatoes. A quarter cup? No way in hell. I use restaurant quality tomatoes that put supermarket fare in the shade but even the supermarket tomatoes never seemed to need sugar at all. A few supermarket brands actually rate pretty close to the “Alta Cucina” brand I use.
With the Altas’ you don’t even have to cook them, they’re so sweet and finished you can “cold cook” them. Just open the can dump it in a bowl add garlic and whatever else you like for flavor let it sit in the refrigerator over night, heat to serving temperature, done!