Well ... duh?
So, you ask Google a semantic/natural language question ... are you actually surprised that Google uses their own results to determine this?
Do you expect an objective determination of this? Would we need a court to decide who is actually the best?
You asked a search engine to give you a subjective response based on the information is has. Do you expect it to give you the results from Bing or Yahoo?
So, yes, the subjective evaluation as returned by Google using their own stuff as a basis is skewed to their own stuff.
Why is anybody surprised by this? Does anybody think Google is going to promote someone else's stuff?
Search results are a starting point. But if you want to know the best burger joint, eat there, or read a whole bunch of different review sites.
This seems to be a lot of hand wringing about the fact that some kinds of search results, which aren't based on objective facts, aren't returning objective facts.
Hell, I've seen user voted polls in newspapers which were as subjective and broken just because the stuff in the area where all the bars were got reviewed more. So all of the downtown stuff was reviewed more. That didn't make it better, just better known.
You asked Google to provide you what is essentially a distillation of opinions, and you're surprised it's not a 100% accurate set of results?
I just don't know why people are surprised by this. Whose stuff do you think Google should be promoting?