My co-worker always gives me a ride home from work. Last week he talked about how he thinks Google Maps selects not the fastest route for drivers but rather an optimized one based on the traffic capacity. In other words, shortcuts are not always the routes that can handle the most traffic load. If the app always showed users the fastest routes to the same destinations, these shortcuts would be congested quickly and no longer ideal. I think this is why shortcuts are meant to be less traveled?