Firstly in an analogue ways - managers are always watching were customers are going/ what they are looking at/etc. The security team at a one co-op bragged that their cameras could read the time on your watch.

Secondly, there are all sorts of new tools stores are trying out to automate this. Software that analyzes footage to generate heatmaps. Or using the in-store wifi access points to generate heatmaps (even if you don't connect, your phone will give away your position when looking for networks). This is especially important in mall settings where they need to calculate foot traffic estimates as a way of pricing storefronts.