Oil is not shelf stable. It can go rancid fairly quickly. Unless you're talking about store shelves, in which case, the dearth of oxygen in the bottle would tend to retard rancidity. Regardless, it wasn't my intent to say that USians expect ``other crap'' (which they do, but that's beside the point), but to point out the typical flavor ingredients.

By the way, the xanthan gum is probably used as a stabilizer to help prevent the vinegar and oil from separating too quickly, and not as a preservative, in case you didn't know what that was.