Fifteen years ago, you opened the yellow pages for the same information. Did you say then, who controls this book? Did you worry about all the power being in the hands of a single phone company?
Likely not, and for two reasons. If the phone company abused it, they'd lose the trust and goodwill that makes the very product valuable, and if it was no longer accurate someone else would come alone and make an accurate version.
Why is that not the same for Google? If their maps become unreliable, won't people move to Bing? If not, why not?