Champagne can be produced in numerous areas, only they can only say they're using the champagne method. In fact the first actual records of sparkling wine predate the various French Champagne producers (e.g. Dom Pérignon) in Italy and England, with some suggestion it was England first due to their stronger glass and tendency to add the necessary sugar to wine - for example there's no documentation of why Dom Pérignon spontaneously switch to bottling wine. The English were also the first to see the bubbles as an advantage.
The original French champagne was a flat wine, so maybe Champagne from the Champagne region of France should actually be flat and sparkling champagne (from England) be renamed?