Mustard, mayonnaise, and chile-vinegar sauces like Tabasco or Frank's RedHot are the only sugar-free sauces I can think of at the moment. Most everything else

Mustard, mayonnaise, and chile-vinegar sauces like Tabasco or Frank's RedHot are the only sugar-free sauces I can think of at the moment. Most everything else either has sugar or an artificial sweetener in it--or some back-door sugar, like raisin paste, or fruit juice concentrates. It is likely because condiments came from preserved foods, and those generally require a high concentration of sugar or salt, or a low pH, in order to avoid spoilage. And some are concentrated from foods that are naturally sweet. I think the sweetness was always valued in a sauce, and substituting the previous source of the sweetness with corn syrup or HFCS is a more recent trend, to cut costs. So it's the latter: popular sauces were adulterated with sugar.