If the population switches significantly to cell technology, that will have to change, as will the requirement to bring in a utility bill to prove residence.
If you buy pay-as-you-go phones, your number will never be tied to a location.
Cell phones are extreme personal tracking devices. When a crime occurs it's possible for the police to get a list of most everyone that was within the cell at the time. It's amazing that not only the government has everyone wearing a personal tracking device, but that people also pay $50/month for the privilege!
There are elements of the "poor" who prefer making it hard for governments to not know where they live