Google is peerless and your analogy fails to account for the store not being a disinterested 3rd party. The war between AMZN and Google is bad for consumers because of the precedents it sets as well as the actual market effects. A slightly imperfect analogy that i still think captures the situation:

Google owns and operates a highway and allows gas companies to build filling stations adjacent to the highway. Amazon is only allowed to have their stations off of exit ramps