Guide dogs are better at identifying and navigating around low hanging obstacles and at learning frequently traveled routes by name. The guide dog can also offer suggestions on how to navigate around an obstacle. In a cluttered area, such as a construction zone, a guide dog can negotiate all of the obstacles faster than a person with a cane.
Canes give better information about the details of an obstacle, such as it's specific location, size, dimensions, and shape. While a guide dog would stop for a mail box in the middle of the sidewalk, he has no way to indicate to his handler that it is a mail box. With a cane the handler can quickly identify the obstacle. Canes also give better information on the texture of surfaces and the height of objects, such as chair seats.
People with canes experience far fewer access issues than those with guide dogs. The cost of obtaining and maintaining a cane is much less than that of a guide dog. A cane might be purchased for $50-$100 which is less than most programs charge for guide dogs. The cane requires little or no maintenance while the guide dog typically requires in excess of $6,000 in care (food, vet, supplies) over a lifetime.