Why do people believe "white privilege" is a thing?

The "white privilege" is not just a belief in some countries its real facts. Its not because of being Caucasian just the white colour of the skin, I am referring to an Asian country where being white is admired and praised, where doors of opportunity opens up for them because of the colour of their skin. Being white is a sign of wealth in this country because if you are white it means you have money, you had a good education, work a white collar job in an office building, not labouring in the sun. The dark skin is not favoured because they deem them as poor class, no money or education. Even all the skin care products, (soaps and lotions have bleaching ingredients in them) all in the hope that their dark complexion can be rectified to be white.
Its not racism if they are the same nationality but it definitely is prejudice according to skin colour.