My local supermarket offers me a small discount in return for receiving targeted advertising based on my purchases.<p>So why doesn't Google pay the supermarket to access that purchase data? Then it could, say, show me toothpaste ads when it knows I'm due to buy more toothpaste.
First, keep in mind, Google doesn't do any advertising. It simply provides a medium for others to travel through.<p>Next, are there brands using Google to advertise toothpaste? Do they need that data to do that? Are there possibly other signals that are as telling / effective?<p>Finally, how - without being more creepy - is Google going to buy that data and tie it back to you *exactly*?