Big brother is not on pay phones
Why did the government opt to spend tens of millions on free cellphones? Because they can be tracked. Pay phones at one time were everywhere. The myth is that cellphones simply killed them off through the process of natural selection.
That's like saying radio killed newspapers, TV killed radio, Internet killed TV etc. There is always room at some level for these varying communication methods to coexist as long as there is a level playing field.
But when that field becomes skewed by political favoritism the free-market mechanism becomes choked off. The remaining dominant technologies, in this case cellphones, text and emails, are now subject to control.
The remaining pay phones get used by a surprising number of people just in different ways. Mostly people make toll-free calls from pay phones since the government mandated that these calls must be free. Yet toll-free calls are not free on cellphones. Cellphone customers know to use a pay phone when making toll-free calls because they are longer in duration and eat up a lot of cell minutes. Most people also know that big brother isn't listening in, at least not without my knowing, because I own the pay phone.