You might be giving Google's PR a bit too much credit there, at least its current PR. A large part of their reputation in the minds of the general public (who don't keep an eye on the machinations of the ad tech world) comes from inertia from their useful products particularly from times when “do no evil” was still a goal for them, and the fact that people just don't think the extra step “if this is free, how is it being paid for?” and might not even care if they did. Most people who are not into tech/business/both never even knew or cared that Google's income is mostly ad based, so they had nothing to forget in that regard.