“An’ a little bit o’ sugar, ..”
Never heard of an Italian who put sugar in sauce. I won’t touch sauce with sugar in it.
Sicilians add a spoonful of sugar to their sauce.
The Corleones were Sicilian.
A spoonfull of sugar cuts the acidity caused by the tomatoes. If the acidity doesn’t bother you or your peeps, don’t use it. A spoonfull doesn’t make the sauce/gravy sweet.