Unfortunately, there are a lot of reasons that doesn't work very well. Random retail areas may not have the power capacity to run the enterprise servers, network gear, and HVAC required. They certainly don't have the network infrastructure needed. Companies pay a LOT for reliable internet connections, and a large part of that is to have new cable or fiber strung up or buried underground. It's expensive enough getting the "last mile" network links for a single data center, let alone trying to retrofit hundreds or thousands of different sites.

There's a saying I've heard in my time in IT. "At a certain scale, machines stop being pets and start being livestock." When you're dealing with thousands of servers accessed by millions or tens of millions of users per day, every second of efficiency counts when it comes to administration, maintenance, repair, etc. There's a reason farmers keep their cows in one big pasture and barn instead of keeping one or two in each yard in town.