There were two women in the mid- to late Victorian era who were notorious for not wearing underwear under their riding habits (because the habits were cut so tight they had to be sewn into them) and one of them was notorious courtesan Skittles, and the other was the Empress of Austria. So too right it was characterisation. But also, even pov characters who care about their appearance are going to care about how their appearance differs compared to their own baseline, not how it appears in general.