What I forget, and I shouldn't because I used to be there, is that even a person who doesn't follow or believe in fashion still has a very, VERY firm sense of what they want to look like.
Alice brought that home to me last year when she wanted a pair of boots. She who had lived in slip-on black Merrels for four years (she doesn'r grow very fast) wanted something she couldn't even describe very well, but when we went to Target she walked down the aisle, sorting and discarding options until she came to one in particular. And that was the one. Mid-calf, brown suede elf boots, with a zipper up the side. She wore them all through the school year. When the zipper broke this week, we had to replace them.
This year, the choices were heavily skewed towards Ugg equivalent boots, kind of clumpy and way too warm for her, but we found a couple choices she kind of liked, and she walked out with mid-calf, purple suede elf boots that perfectly matched the purple hoodie shirt she wears.
This is just to say that self image is a deeply mysterious thing.