 The aerodynamic design of a car body is engineered to maximize fuel efficiency. In order to minimize drag and instability, designers have to consider the law of physics. Since those laws are absolute, every car that is designed for maximum fuel efficiency will end up with a similar shape. The same can be said for any number of things that consumers use and or come in contact with every day. In each case, it's a higher standard of quality which means less differentiation. Welcome to the age of average.