monoculture (n) ~ a system with very low diversity; a potentially dangerous hegemony that breeds uniformity, complacency and (eventually) totalitarianism
So, these dresses are like the garment industry's answer to generic brand supermarket foodstuffs: All manufactured in the same factory by an inconspicuous label and then sold by a large retailer under their particular 'brand' at prices well below the designer products they echo. The only difference is that instead of descriptive, unassuming generic brand product names like "Deodorant Soap" or "Chocolate Syrup," we have "Look Over Your Shoulder Dress" and "Western Sunset Cowboy Boots." Viva la value...