I don't really think that's the case (here, yet) but I do think it's scary that it's so easy to do that its not just done as a proof of concept but actually used in production in a low tech industry.
Gathering demographic or sentiment without storing, cross referencing (has this person been here before etc) or otherwise using the data for anything such as targeting ads - is kind of acceptable. I mean it wouldn't be hard to do that manually via a camera if you wanted to test the engagement of an ad. I'm sort of hoping this is just some tech project from a university or something, and not an actual product you can buy and hook into some adtech service.
Edit: as someone else pointed out - it's not a proof of concept it's an adtech off the shelf product. Because of course :( http://www.adflownetworks.com/audience-detection/