Interesting essay about how Google's lack of transparency is hurting their trust:
The reality is that Google's business is and has always been about mining as much data as possible to be able to present information to users. After all, it can't display what it doesn't know. Google Search has always been an ad-supported service, so it needs a way to sell those users to advertisers -- that's how the industry works. Its Google Now voice-based service is simply a form of Google Search, so it too serves advertisers' needs.
In the digital world, advertisers want to know more than the 100,000 people who might be interested in buying a new car. They now want to know who those people are, so they can reach out to them with custom messages that are more likely to be effective. They may not know you personally, but they know your digital persona -- basically, you. Google needs to know about you to satisfy its advertisers' demands.
Once you understand that, you understand why Google does what it does. That's simply its business. Nothing is free, so if you won't pay cash, you'll have to pay with personal information. That business model has been around for decades; Google didn't invent that business model, but Google did figure out how to make it work globally, pervasively, appealingly, and nearly instantaneously.
I don't blame Google for doing that, but I blame it for being nontransparent. Putting unmarked sponsored ads in the "regular" search results section is misleading, because people have been trained by Google to see that section of the search results as neutral. They are in fact not. Once you know that, you never quite trust Google search results again. (Yes, Bing's results are similarly tainted. But Microsoft never promised to do no evil, and most people use Google.)