The OP made two mistakes in his opening sentence.
I quote:”The Gemara (Kesuvos, 72A) states that a woman who goes out with her hair uncovered gets a divorce without a Kesuvah.”
1. This is a mishnah, not a gemara. Yes, I know it is the tractate, but there is a difference, and the difference is important.
2. The word ???? does not mean uncovered. It means wild or unruly. This definition is the crux of the entire issue. If it is improperly defined, the discussion loses value.