My presence in private is a protected right in the United States. Being able to track which office I go into in a complex, tracking which room in a house I am in, etc. These types of things require a warrant based on reasonable suspicion and this has been ruled on numerous times. If you're moving from place to place in public view, sure, that's allowed. The police can also follow you and watch you enter a building, but what is the functional difference between preventing access to my house to watch me move from room to room and using cell phone data to track me. My carrier is someone I contract with. I pay them. They should be working in my favor to the fullest extent of the law. While I sympathize with overburdened police forces and tough crimes there's a reason we have these protections in place, to prevent a police state where the police are more beholden to the state than the public it is expected to be serving.