Here's my take on this:
1) I live in the US, i happen to be learning guitar in the US, i don't care how they do it in other countries (sorry, i'm somewhat closed minded, things are simpler that way)
2) The guitar is a complex enough instrument, i don't need to make it any harder.
3) When my guitar teacher speaks, it is 2nd only to the voice of God... (and my wife) Do Re Mi is the major scale, the musical alphabet starts with C, because the C major scale is unique in that it does not contain enharmonics.
However, i did learn:
1) Do Re Mi is known as "soflage", a method of "ear training" music (simple definition---see Brian' post) This backs up my previous theory of what i referred to as "tonal representation" of the major scale.
2) In other countries they do represent the key of a song by the soflage method.
3) I'm glad i'm not learning guitar in those countries!
Who said closed minded people couldn't learn something? We have to ask the question: What would Andres Segovia Do?