How is what you described different from TV? On TV, you can target so many demographics indirectly by buying ads on shows they like. Companies like Nielson hav

How is what you described different from TV? On TV, you can target so many demographics indirectly by buying ads on shows they like. Companies like Nielson have been reporting on the demographics watching shows for decades. You can also target geographically at least down to the county-ish level. TV stations and Google both know who is watching what and selling access to their customers to advertisers. Google might be a bit more sophisticated than TV, but besides "retargeting" (following you around different sites) they use the same basic techniques and offer the same things to Advertisers