If the U.S. Government wants to know who is communicating with whom in a world without modern technology, it can hire n government workers to sit at a desk and write down the address information on all the envelopes passing through USPS in a day. Expensive? Yes. Impossible - to the entity that fought WWII, landed on the moon, and continues to maintain a pretty much stable country of 300 million people? No. Our government may suck at cost-efficiency, but it is great at throwing resources at things that scale O(n), like the number of postal workers required to handle n letters.

There are good arguments to be made that it's not the government's place to know who is communicating with whom anyway, so it shouldn't be allowed to. If this is the case, than it shouldn't be allowed to by any means.

But how does a shopping mall not have the right to watch people move through its store? If it's wrong to watch the EM signals people emit as the move through, then is it also wrong to watch the light they reflect? I've seen employees doing traffic analysis in museums pretty frequently - in fact art museum security guards do it all the time. They could do the same in a mall. They could even park an employee with a clipboard on the second level and map out people's movements between stores below. Focus on one store at a time, find out where all the people leaving that store go. You'd still get the same result - the general trends of how people move around the stores, based on our evolutionary "tracking" ability - the Orwellian step of correlating neural impulses from the eye as belonging to the same object in different positions. Which is exactly what this cell phone tracking system does, except with MAC addresses instead of faces and hairstyles.

I say this to emphasize that not all tracking is bad. Correlating different sensory input with past and future inputs is a large part of being human. Hell, in a small town 50 years ago, the general store owner probably knew you and what you've bought before and who your friends are. The post office worker could recognize a scandalous pattern of letters are tell your family about it. That's way more invasive than this. Involvement of machinery is not the difference between good and bad tracking.