Albertsons and Macy's uses facial recognition on customers, but this article gives us little information on how.

We must reject the idea that businesses deserve the freedom to do facial recognition on video images in and around their premises, or the freedom to make videos and transmit them elsewhere, or regularly save them for more than a few weeks, This supposed freedom conflicts with the privacy that humans beings deserve, and it facilitates the repression than US cities and agencies are already eager to commit. These include Atlanta and Florida.