Learn English – What does “has got to be” mean

It is a popular idiom though it has a wide range of meaning depending on the context. In your example I would venture to say, though not having read the book, that it's a compliment implying the woman is brazen or brave. "She has style" is a complementary idiom that usually means the woman did something "in her own unique way" or "in an unexpected way."

The problem is that the terms correct and incorrect are used in situations where non-standard, unusual or unlikely would be better descriptions.

Double negatives are non-standard but "correct" in certain dialects. The phrase a strong smoker is an unusual collocation (cf. a heavy smoker), but can hardly said to be incorrect. How have you got that black eye? is an unlikely sentence, but again cannot said to be incorrect.

Nevertheless, the term incorrect can be applied to large areas of grammar. It is simply incorrect to say: Understand do I you not or She has two dog or I will play football yesterday.

There's a case for saying that the authority in these cases is the grammatical hard-wiring that would lead every native English speaker to reject such formulations.