If women weren't so obsessed about the size on the tag, there would be no need for vanity sizing. Over the years the sizes have been cut larger and larger, so what was a size 10, 10 years ago, is now a size 4 or 6, it's not that people have gotten that much smaller, it's just we all want the smallest number on the tag as that makes our ego feel better.
There needs to be a more relative standard, that is a size 10 has a 30" waist, a 32C cup bust and some other more standard measurements, rather than size 10 might have a 26" waist in some shops and 34" in others, all a size is, is a guide to help you choose a piece of clothing when you walk into a store.
We're all built differently, so some brands are cut curvier, and some straighter, which is fine, it's more about the wide variation of sizes that I have an issue with.
Time to get off my soap box.