There are some standards. The ingredients are listed in descending order of size (ie the first is the largest).

They can get around this in a few ways (though this isn’t really relevant here), such as for example preserves having this ingredient list: blueberries, sugar, corn syrup. Even though the amount of blueberries is technically larger than both sugar and corn syrup, sugar and corn syrup (still basically sugar) can add up to much more than the amount of blueberries. By including multiple types of sugar they can sort of hide the fact that the largest ingredient is some form of sugar