My answer to this is, you cannot see everything with a cane that you can with echolocation. Let's take a close look at the difference:
One Data PointIn order to see an object with a cane you have to move the cane to the object, touch the object with the tip of the cane and then move your cane around to see other parts and other surfaces of the object. It's safe to say that the cane provides only one "data point", meaning only one piece of information at a time. It may take a few seconds to touch something in a few places and actually get an understanding of what it is. Echolocation, on the other hand, offers several data points in a single click - an instant. One click can uncover the shape of several surrounding objects.
Beyond the Tip of the CaneThe cane is a physical object about 4 feet long. Essentially this is the range of one's perception. If the cane is the only thing you are depending on to navigate. Then anything greater than 4 feet away is completely invisible to you. With echolocation the range of your perception can be up to several hundred feet. You can see buildings, trees, people, hallways, entire rooms much larger than the length of your cane, and you can see them in an instant, or at least after a few clicks.
Side VisionWhen walking with a cane, it is generally swung back and forth in correspondence with one's footsteps. It is swung in an arc to determine anything on the ground within the walking path. Unless you swing the cane way over to the side and try to touch something you will not see anything beside you. Echolocation of course offers perception of objects on both sides of you, objects at head level, objects above you, and even behind you.
Physical ContactOf course with a cane you must make contact with the object you wish to understand. Sometimes that can be someone's shin, something fragile or something that causes a loud noise. This can be arguably more intrusive than making a click sound with your mouth. The only thing that makes contact during echolocation is sound waves which, to my knowledge, have never been observed to bruise shins.
It is encouraged that people supplement the white cane with echolocation and learn to use them both together because, while the cane acts as an excellent and irreplaceable safety device, echolocation gives you a much broader and more complete view of the world around you. Echolocation isn't a huge life change you have to make all in one stroke. It's easy, if you have an open mind and are willing to try new things, to take it a little bit at a time and experiment with it on your own to get comfortable. And know that you never have to relinquish the security and assurance that your cane provides.