https://talkingpointsmemo.com/edblog/a-serf-on-googles-farm
> But here’s where the rubber really meets the road. The publishers use DoubleClick. The big advertisers use DoubleClick. The big global advertising holding companies use Doubleclick. Everybody at every point in the industry is wired into DoubleClick. Here’s how they all play together. The adserving (Doubleclick) is like the road. (Adexchange) is the biggest car on the road. But only AdExchange gets full visibility into what’s available. (There’s lot of details here and argument about just what Google does and doesn’t know. But trust me on this. They keep the key information to themselves. This isn’t a suspicion. It’s the model.) So Google owns the road and gets first look at what’s on the road. Not only does Google own the road and makes the rules for the road, it has special privileges on the road. One of the ways it has special privileges is that it has all the data it gets from search, Google Analytics and Gmail. It also gets to make the first bid on every bit of inventory. Of course that’s critical. First dibs with more information than anyone else has access to. (Some exceptions to this. But that’s the big picture.) It’s good to be the king. It’s good to be a Google.
> There’s more I’ll get to in a moment but the interplay between DoubleClick and Adexchange is so vastly important to the entirety of the web, digital publishing and the entire ad industry that it is almost impossible to overstate. Again. They own the road. They make the rules for the road. They get special privileges on the road with every new iteration of rules.
There are a lot of people bothered by this, so this data discovery could prove very expensive for Google.