Google how the human eye works. The rods and cones. Colour and harmony between colours is rooted in our biology. Your iphone screen looks very unnatural, unattractive, to a dog or a goose. They see very different colours than we.

Our affinity to bright red is tied to how we used it to identify ripe fruit. Notifications, things they want you to click/grab/poke work best in red. You dont see many brown buttons on websites. We dont like touching brown the way we do red.