It's also useful to recognize that for some of Google's lines of business, the payment offered is not money, but attention (or perhaps habit). Then, searchers are again customers, after a fashion.
This better recognizes the searchers' customer-like power, in some dimensions. Otherwise, as just the 'product', were they mined from the ground? Grown like crops? Manufactured? No, their attention was acquired in a voluntary, market-like but non-monetary exchange of value for value.