Champagne is absolutely not a "generic" product in the US.
While some California wines were and still are sold as "California Champagne", there was a court decision back in 2006 which affirmed the same protected trademark for Champagne as in the rest of the world, with the caveat that wineries already using the "Champagne" name would be grandfathered in and permitted to continue doing so.
A bottle of Champagne made in the US will be labeled with its origin, and no one can start a winery and start selling Champagne in the US. That's not the same thing as "generic".
Champagne isn't a trademark and it's *generic* in US. What happened that in 2006 US signed an agreement with EU. Obviously everything can change.
https://www.ttb.gov/system/files/images/pdfs/rulings/2008-1....
I guess it's "generic" in the sense that everyone calls a sparkling wine "champagne", same as everyone calls a copier a "Xerox machine", but if some other company would try to sell their copier using the Xerox name, they would still be sued by Xerox (the company)?
At least here in Europe, even children know that “sparkling wine” and “champagne” refer to different things.
There is a kinder variant for such - prosecco, which can actually mean OK quality (within sparkling stuff bounds, which are not high).
But yeah calling anything Champagne apart from stuff coming from Champagne is a bad form and looked down upon a bit. Small kids do such mistakes and thats fine, adults shouldn't.
Not all adults care about the origin location nor should they.
If you’re ordering “sparkling wine”, you are not going to get a wine made using the méthode traditionnelle.
You will get an entirely different style of wine.
The origin location is really secondary. “Franciacorta” gets you something like Champagne, “sparkling wine” does not.
The US legal system doesn't have the concept of "trademark" in the way you're using it, that word means something else here.
And no, "trademark" definition aside, it's not "generic" in the US by any definition of "generic" commonly used in the US, legal or otherwise.