Sizing and the Fashion Industry

Women, in general, tend to be influenced by very small numbers. Different clothes can make a woman feel good or bad about herself. Although two items are in all actuality the same size, if one is marked to be a larger number/size, the woman will gravitate to that smaller number. For instance, I have a pair of jeans that is a size 6. I fit into them just fine. However, today I put on a pair of khakis that measure the same and fit the same as those jeans. The difference is not in the appearance, but in the tag-identified size: 10. I admit, I have felt like a fatty all day long, yet my logical self says that I shouldn't. They are the same size, they are just marked differently as they are made by different brands.
I find similar inconsistencies with children's and infant clothing. It would make it a whole lot easier to purchase these items if they were more standard across the board. So, instead, I get to sort through by measuring different outfits to see what size my girls actually wear. A size 0-3 months item for Gianna can either swallow her or be just right at this point, yet newborn clothing still fits her. Emily, in like manner, wears pants ranging from a 2T to a 3T whereas her shirts can be anything from a 2T to a 4T.
All in favor of standardized sizing, say "Aye!"
"AYE!!" But, in the meantime, I'll continue feeling like a fatty as I wear my size 10 khakis and feel thin wearing my size 6 jeans.