There was a story about it right here on this site:
"A previous report from Digiday, described as being "pretty accurate" by Bank Innovation sources, claims Apple plans to monetize its mobile payment system by integrating iAds with Apple Pay. This iAds portion of the loyalty system allegedly will use iBeacons and Bluetooth LE to push targeted ads with a "tap-to-buy" button to customers while they are visiting a participating merchant."
They know your location, the merchant you're using, the card you're using and many more details. Try taking your head out of the sand and you'll see stuff that's right in front of your nose.