Fundamentally what they've deployed here is something a lot of organisations struggle with or don't even recognize as worth having - A reliable edge which you can trust sufficiently to form the functional core of a site.

For a restaurant chain this is something worth putting the development effort into because once you've figured it out and ran it for a few years to demonstrate it's reliability you can pitch the shift from a network-optional edge at each site to a network-dependent site with intelligent components hanging off it and depending on it. That's a pathway to having a major competitive advantage in the medium term that your competitors won't be able to put into place overnight once they realize you've left them behind.

You can't get there with the amount of effort often put into untrusted edge sites like this - aka a pc in a cupboard. You also can't get there with cloud when the weakest element in the chain is unrealiable site connectivity.

They could have done it in a lot of different ways, but going with cheap commodity hardware and avoiding expensive cluster license nonsense (vSphere etc) were smart choices. Spend that money on a compenent centralized tech team rather than vendor shinyness, and you can do a hell of a lot more (and often move faster, to boot).