L4key.. You are the one being pedantic! I just answered a simple question with a simple answer.
What did the originator ask? "Q. at which alt do you actually begin to fly over a country rather than just the space above it?"
He then provided a few possible answers.
The answer I gave - "The instant the wheels leave the ground. You are over a country when you are in the space above it. Where else could you possibly be?" was surely totally correct?
I wish you luck with your dream; I had a similar one about 55 years ago. Oh yes, I'm a lifelong spotter too!!