You are correct, Jim. Services, equipment, and even support should really be tied to an address. In this way, a company can know what services are currently available, and even more importantly, study the history of a location.
The current system, most of these ISP systems actually, ties an address to a client. When a new client moves in, there's no way to track the history of trouble. Is there a line going bad? Is there's a pattern of wireless issues? You can only solve some of these things by studying patterns. Patterns take time. When the history of a location is wiped out with each new tenant, the provider really cannot know what is truly going on.
This is exactly how systems developed for cable and telco track things. Customers are tied to addresses. Addresses are not tied to customers. I've never seen an address change every year or two for a customer who remained in the same place. However, I often see a customer change for a given address.
Most WISPs use systems that were cheap and evolved from dial-up billing systems. The fixed location services world should have had billing systems that were designed correctly for that world. However, many WISPs also had dial-up and so they just added the new services to the old system. They didn't realize how much information this model lost them.