Because each of them exerts an emotion that we perceive on a subconscious level. We identify it especially in the world of advertising, as big brands have made their color of identification, we need only think of a pub. Coca Cola ...
Different meanings for places, times and cultures. White is associated with purity, whiteness, brides wear white, we give white flowers, our furnishings and homes are white. For most Asian countries it is associated with mourning at a sad time.
In ancient Egypt the sarcophagus was covered with sumptuous red cloths and mourning clothes were red. Regarding this topic there would be many other colors to list, including yellow, as they say: when in Rome, do as the Romans do.
Medieval medicine associated each color with an emotion, consequently a cure, and each organ responded better to one color than another. Before in Egypt and before that, Greece. When we are afraid the blood goes to the vital organs to protect them, in fact it is said: you are white from fear. When we are red we are red from anger or shame, because our blood rises in response to the insult or injustice suffered " erubescere " from Latin
( to become red in the proper sense ) or both to be ashamed.
I will delve into this topic for you, and I can tell you that we are going to see see a lot of it !