[gindely]

Well, the conveniently indicated grams on the packet are not units of weight - they're units of volume. So you've got two kinds of units of volume in your recipes: milli/centi/decilitres, and grams of butter. But it's fairer than the grams of flour I've been ranting about elsewhere here because at least the manufacturer can have some responsibility for fine tuning it to their product!

[qtk8]

Do you have any source for your claim that "grams of butter", "grams of flour" and "grams of sugar" do not all refer to the SI unit "gram"?

I live in Europe and have always weighed exactly 100g on the scale, whether I was asked for 100 grams of butter, sugar or flour.

[SAI_Peregrinus]

They are the SI unit of mass. He's just saying that because it's indicated by lines on the package that the actual measurement is done in volume, and the conversion is implicit by the scaling. Where he goes wrong is in thinking that it's implying that "grams of butter" is a unit of volume.