Why use words like black market?

Black and white in language was not used to refer to the colour of people's skin.

"....there were no “white” people in Europe before 1492. With the transatlantic slave trade, first Indian, then African, Europeans increasingly saw “white” as a race and race as an important human characteristic."

Before this period, black referred to things that could be done under cover of darkness.

Sorry friends, there is nothing racial about black market, etc.