In one sense you are correct that Google is "free" because one does not pay cash directly to Google to be listed in its results or to preform a search.
But in another sense, Google is not free at all. The fact is, Google lives and thrives off of the data generated by the public. Yes, Google employees smart people. But its real value is derived from the underlying public data that Google gets- for free.
Google search works because the world allows Google's bots to traverse their websites freely and index their content. Google translate works because the EU and other governments translated their documents into many languages and then gave them away to the world. Google Maps works because of GIS information gathered on the public's dime. Gmail is able to operate because users allow it to mine their personal messages to better tailor advertisements.
Google is built on top of and depends on the public- both to be its customers and to be the source of its products. It has taken the market in search, email, browser, and mobile. And, for the most part, it has created some great tools for people to use. But there is a minority of people whose lives are affected by Google for the worse. Its important not to marginalize these people.
This is a non-democratically elected institution whose policies and actions have more effect on people's lives than the governments of many nations. Those policies and actions ought to be looked upon critically by the people.