Designer Labels

Now a days, there are only some clothing and accessories that are terms "Designer Labels." Why is that?
When referring to "Designer Labels", people usually mean expensive, "fashionable" things such as DKNY, Dior, Gucci, Coach, and other such labels.
Since we are taught that design is everywhere and can be anything; I would like to assume that every article of clothing and accessory we own is in some sense a designer label.
A designer label is like a signature clothing someone has created and design as their own. So, the pair of 15 dollar P.E. shorts I am currently wearing is in a sense, a design label.
What really intrigues me is how something can become a popular "designer label."
When a designer is successful in the fashion industry their products' net worth start to rise. How does this happen? How can a simple pair of shoes be worthed up to 500 dollars? Sure, the material used could be really high quality material, but it can't possible be that expensive can it?
Its so strange that society can be so judgmental on a person depending on what they wear.
Even at a young age children are conditioned to judge their peers based on their clothing and accessories. As an example, Let's go back to a childhood memory of mine:
In the 7th grade I remember receiving a pair of tennis shoes from payless because my parents were not very rich people. These shoes were nice; they were basically imitation shoes of the Addidas brand tennis shoes. I never had a problem wearing payless shoes- it was cheap and it served its purpose. This was not the thought of my classmates- I was teased countless times for being poor and wearing payless shoes. My classmates knew that the Addidas brand name shoes had 3 stripes on each side of the shoes and my shoes had 4. That one extra stripe on my shoes told the world I was poor and that I could not afford the popular Designer Label of Addidas.
There are many reasons as to why something may be referred to as "designer label", whether it be the quality, the style, or the name, but I think everything is a designer label- clothing and accessories were designed and created by someone. This is their "designer label".