I've been given or bought several Moet-Chandon bottles over the years, and I would not be able to tell you with certainty whether they were filled with wine from the Champagne region. Anecdotal for sure.

I would also argue that you could use any reasonably French sounding place name, 'Trois-Rivières' and people would make assumptions.

And that's imho the selling point of (at least the lower end) champagne. I still do that occasionally. A $20 difference is a pretty small price for a "signal". It's not stupid just because the content is indistinguishable. I pay for the label - because the label is the effect! It's the product!

That's also why such producers need to be careful with others using their name. They are selling a name while everyone else is selling wine.

And most of the price difference results from cachet anyway. A benefit of living in France is that there are plenty of great wines available for less than 10 Euros. They don't get exported because, I'd imagine, it's probably not cost-effective to do so.