Why would Harley-Davidson put as much emphasis on consistency of quality as it does on level of quality?

Harley-Davidson’s customers can spot each other instantly by the iconic black, white, and orange logo on their motorcycles, clothing, and saddlebags. More than a century after the first Harley-Davidson motorcycle hit the road, the company’s annual worldwide sales have risen as high as $5 billion.
Harley-Davidson dominates the U.S. motorcycle market, and sales are also strong in Japan and Europe. Its annual output covers 31 models in five product lines (Sportster, Dyna, Softail, VRSC, and Touring).