Google’s attempt to “correct” your searches almost never works. So why do they do it? Didn’t they test it? Aren’t these supposed to be the smartest people in the world? (Chuckles.)
The answer is that Google doesn’t care if the algorithm works well. In fact, it’s better if it does not (for them). The reason is that they are attempting to herd you, not help you. If you get used to shoddy results that aren’t really what you are seeking, all the better.
A shocking number of people (like John Scalzi, Kevin Drum and those morons at Grumpy Rumblings of the Untenured) somehow believe that corporations are out to to help them. I have no idea how they can believe this, but it seems a particularly prevalent cognitive error among Baby Boomers and economists. Regardless of what they think, corporations are very much not out to help you. In fact, they don’t give a crap about you at all.
Google is prodding you the direction they want you to roam, then putting up a fence and telling you that’s the entire world. Most people, it seems, are just fine with that.