From the article: "The size of your house is a pretty good proxy for your wealth."

Amazon already has your address - so they already can get detailed maps of your house, tax records, likely income, and on and on, from other records. They can link to all your public data (Linked In, FB, Zillow, whatever else is for sale) to build massive profiles of you, your purchase history, your neighbor's purchase history, and so on).

This purchase is more likely to get more robot expertise, patents, and capability as they want to automate more of their entire pipeline of moving goods. That is where the big money is. Saving a few percent on a several hundred billion pipeline via automation is massive.