I think most grocery stores have something similar. When I worked at Giant about 15 years ago, I used a self-contained scan gun (basically an overpriced Windows Mobile 5 PDA stapled onto a barcode scanner) when I had to do "the walk," which was the hourly store inspection. Decidedly lower-tech than even a badge reader, but it got the job done and my boss didn't have to know where I was during my time off.