These engineers are /not/ the engineers that are in charge of designing or running the systems that sell ads. In fact, those are two completely different divisions of the company. (If you would like to learn more about how Google works from the inside, I suggest reading Steven Levy's book "In the Plex")
Just because you do not pay for something does not mean it is not a product. If search was not good, people would go to a competitor. This is how Google got to where it is today, and bing.com is just a click away. This thread is about the quality of Google search results, and your argument is that Google does not care about the quality of your search results because they allow you to use it free of charge by inserting labeled advertisements.
To me, this is not a logical argument -- your emotions and sense of being wronged have taken over.