It’s no secret that there’s a rising premium on “being yourself, being an individual, bringing your full self to work, broader expression of who you are,” says Scott Cawood, the CEO of WorldatWork, a global association for human-resources professionals. (WorldatWork, he notes, doesn’t have a dress code.) He traces the codes’ modern existence back to the Industrial Revolution, when standardized, indoor workplaces became the new normal. Before that, laborers were freer to dress in ways that suited their duties, often on family farms, and had smaller wardrobes to begin with. No one had to consider whether yoga pants were appropriate for gathering the day’s eggs.

As the norms we know now were developed, the people in power made them in accordance with their own preferences. “You traditionally had men in the C-suite, and they had certain conceptions of how men and women should look. That’s why there was so much concern about can you wear skirts, can you wear pants,” Cawood says. Some of those rules are still enforced in workplaces that prize formality—fine-dining establishments, white-shoe law firms, Congress—including guidelines about hosiery, makeup, and women’s hairstyles. Doing away with these standards is a question not just of gender, but of class: The more comprehensive the expectations for presentation, the more resources required to meet them, and buying a closetful of work wear is a lot more expensive than just using what you already own.