Hidden kickbacks are a racket though. Google has very deliberately been making their ads less and less distinct from their top search results, in a frog-boiling way.
Remember when they made a point about how they had a blue background and were on the right rail? Then they got moved above the organic results, then the blue changed to yellow, and every PM working on SERPs shrunk the size of "sponsored" and made the yellow a shade lighter for the next 5 years and got a nice bonus for it.