I've been assuming that deals of this kind are commonplace, but it's unusual to see one acknowledged publicly.
“Google and Mastercard Cut a Secret Ad Deal to Track Retail Sales”
Mark Bergen and Jennifer Surane, Bloomberg, August 30, 2018
For the past year, select Google advertisers have had access to a potent new tool to track whether the ads they ran online led to a sale at a physical store in the U.S. That insight came thanks in part to a stockpile of Mastercard transactions that Google paid for.
But most of the two billion Mastercard holders aren't aware of this behind-the-scenes tracking. That's because the companies never told the public about the arrangement. …
It works like this: a person searches for “red lipstick” on Google, clicks on an ad, surfs the web but doesn't buy anything. Later, she walks into a store and buys red lipstick with her Mastercard. The advertiser who ran the ad is fed a report from Google, listing the sale along with other transactions in a column that reads “Offline Revenue” — only if the web surfer is logged into a Google account online and made the purchase within 30 days of clicking the ad. The advertisers are given a bulk report with the percentage of shoppers who clicked or viewed an ad [and] then made a relevant purchase.
“India Will Install Cameras in Classrooms amid a Rise of Surveillance Measures in Asia”
Rosie Perper, Business Insider, January 21, 2018