So, the first thing that came to mind was Target's datawarehouse market research work that got a lot of press a month ago. Some vocal people were up in arms about privacy, instrusiveness, money, etc., but this here move by Walmart should really put those peoples' minds at ease.
Here is a company with more money than god, yet they have to buy a company in order to spy on their (potential) customers with any degree of ROI and/or effectiveness, and only WRT date-based information. If you don't agree that they're spying, I think you can at least allow that this is (what could be known as) a sledgehammer approach to market-research.