As an engineer, it pains me to say this: Marketers are the smartest people in the world.
Consider a can of Red Bull:
Now consider the cover of a recent undergraduate introductory microeconomics textbook:
Within the text are case studies illuminating Red Bull’s very innovative marketing strategies. The textbook itself, with this cover and these case studies, subtly advertises Red Bull. The move is absolutely brilliant.
We’ll probably never really know if Red Bull had a direct hand in this, or if they simply made such an impression on the book’s authors that the authors ended up advertising Red Bull for free. If the latter is the case, then Red Bull clearly owns the customer.