I think most people do assume the same with search results. How many do you think assume that the ads on the TV they see could be different than what the neighbor is seeing when watching the same channel with the same cable company? I think a lot of people assume that others see the same news and the way people act you'd think they assume that others see the same things in their newsfeed/timeline / facebook thing - and wonder how others could have a different view.

Even when I explain how ads can be different, I don't think people really want to believe it, or understand it, and they certainly do not realize the power of these targeting abilities..