pharmaT, I'm rather surprised that you didn't understand that that is exactly the point I was making.
The test says what your DNA is; not what your ancestors are.
Expecting to find out what percentage of your ancestors came from where ... nope, that just won't happen.The Ancestry television commercial has the woman saying "I am 26% Native American".
Not in any meaningful sense, she isn't.
Apparently her DNA is 26% Native American (and since it's Ancestry saying it, I would take that with a grain of salt anyway).
The test does not show that SHE is 26% Native American.
When I say I'm 100% English except for a greatx4 grandfather born somewhere in Ireland c1770, I'm talking about my ancestry, not my DNA. I think that's how most people understand the concept.
It is absolutely misleading for Ancestry to tell people they are A% this or B% that or C% the other thing. Autosomal DNA simply does not tell you where any proportion of your ancestors were from. It's just a pretty meaningless bit of data.
As you say, this woman's "26% Native American" DNA could well mean that she has one Aboriginal greatx4 grandparent whose autosomal DNA just happened to be the bit that got passed down to her.
It isn't going to get her tribal membership in any Native American group in the US.

That depends on
ancestry, not DNA. Just the way most of us think of "what we are".