Julia Child says about butter in her book about French Cooking: "It has recently become a habit in America to call unsalted butter, "sweet butter"; there is an attractive ring to it. But technically any butter, salted or not, which is made from sweet, unmatured cream is sweet butter."
An interesting thing is that in Spain for example, they rarely use butter or margarine. When walking into a breakfast bar they serve you a toast with olive oil and if you want garlic rubbed on it they give you that. My Dad always has a toast with garlic, olive oil and parsely in the morning!