There is a kind of onion called a "Vidalia onion," grown in the town of Vidalia, Georgia. They're a sweeter onion, which is unusual, which is why it grew into a brand.
However, because of this, a lot of people's first exposure with a sweet onion is a Vidalia. But not all sweet onions are Vidalia onions. Yet sometimes people still use "Vidalia" to mean "sweet onion" in a generic sense.
I suspect it's very similar, honestly: I don't think your average American knows that Champagne is a place. Their only exposure to the word is via that style of wine. And so they associate it with the style rather than the brand/region.
(Vidalia onions are also protected legally in the same way that Champagne is; a lot of people in this thread saying that that's just some silly French thing don't realize how common this is. In the onions' case, this has been true since 1989.)
There is a kind of onion called a "Vidalia onion," grown in the town of Vidalia, Georgia. They're a sweeter onion, which is unusual, which is why it grew into a brand.
However, because of this, a lot of people's first exposure with a sweet onion is a Vidalia. But not all sweet onions are Vidalia onions. Yet sometimes people still use "Vidalia" to mean "sweet onion" in a generic sense.
I suspect it's very similar, honestly: I don't think your average American knows that Champagne is a place. Their only exposure to the word is via that style of wine. And so they associate it with the style rather than the brand/region.
(Vidalia onions are also protected legally in the same way that Champagne is; a lot of people in this thread saying that that's just some silly French thing don't realize how common this is. In the onions' case, this has been true since 1989.)