Colour consultants. They have a conspiracy going to make us live in an ugly world. The way it works is, people instinctively like pretty colours. Nobody can make money selling us a decision to do what we instinctively like--we could have decided that all by ourselves. So the colour experts have a whole lot of clever sophistry designed to convince us it's very important for us to paint things ugly colours instead, and then we're like "I would never have thought of all those important considerations by myself--just think how awful if I'd naively painted the house a pretty colour that I liked! Good thing I consulted an expert!"
This explains all those buildings in horrible drab grey-beige, washed out greyed down versions of puke green, mushroom, and fucking taupe.