How did the boundaries between high fashion and everyday apparel become less clear after the 1970s?

After the 1970s, the boundaries between high fashion and everyday apparel blurred significantly as the industry shifted toward a more democratic and casual approach to style. Several key factors drove this transition:

• The Rise of Casualness: The rigid etiquette governing dress codes largely disappeared, replaced by a cultural dictum to "do your own thing." In men’s fashion, the tailored jacket and vest were increasingly ousted by sweaters and casual jackets, with little distinction made between day and evening attire.1
• Mass Production and Accessibility: Modern marketing and television advertising brought fashion within reach of the general population. Manufacturers and department stores began producing ready-to-wear versions of high-fashion designs at various price points, making trends widely available.1
• Technological Innovation: The development of synthetic fibers—offering benefits like crease resistance, permanent pleating, and easy-care characteristics—allowed for the rapid and inexpensive production of clothing, further bridging the gap between luxury and mass-market garments.1
• Cultural and Youth Influence: Fashion became increasingly driven by individual expression, music subcultures (such as punk rock, hip-hop, and grunge), and lifestyle changes. The adoption of once-utilitarian items like blue jeans into mainstream wardrobes exemplified this shift toward informal, youth-oriented styles.21