Brands use black to signify exclusivity and glamor.

Some brands are instantly recognizable by a single color.

The color a company uses to brand itself conveys how trustworthy they are to consumers, the quality of their products, and much more.

Like purple, black can also be seen as a luxurious color. “Black, when used correctly can communicate glamour, sophistication, exclusivity,”

Source Business Insider

Black is a color you take seriously.

Just imagine if Haagen Dazs was all black? You'll certainly feel like you need to pay more