Uh Oh DUmmies. One of your favorite "groups" is to blame:
http://www.femininebeauty.info/skinny-fashion-models
I have found that the cheaper the clothes and shoes the larger the size.
Living in my area where designer clothing is to be found in consignment stores, and thrift stores, the first thing I do is to check the label and if I find a expensive designer then I check the size. For years I just passed up clothing in the 4-6 size range until one day Mom came shopping with me, she was surprised to know I had no idea of high fashion, she loves the fashion Magazines allways has.
At the time I wore size 7-8 and here she was grabbing labeled clothing at 5-6 and insisted I try them on. Not only did they fit but some were too big. Reason she told me is that people with money to spend on a $1,600 jacket wanted to think they were smaller then they were. So the fashion designers labeled them 3-4 sizes smaller then they are. Same with shoes, the more expensive the smaller the size. A pair of Sears or Penny's best Jeans I have to wear a size 8 but if I find big label jeans in a consignment shop the size is 5-6. Same with under ware , a bra sized 34 B at Walmart goes by the size 36 C at the top stores.
Really, the huge prices of designers clothing is about vanity.
Men fixate on their size of their manhood, woman fixate on the size of their clothing.