When people believe they are being watched they act differently. Essentially you are coercing them. People need a reasonable sense of privacy to be able to act freely so, to me, this means that privacy is a central requirement of freedom.

There are legitimate reasons for some ability to conduct surveillance, but without a cost any surveillance method becomes mass surveillance. That cost must be human, it must scale in human time, or it turns into mass surveillance since without a human cost all it takes is one person and one button to watch one or a hundred thousand people.

Technologies like flock have no human scaling cost. They run 24/7/365 and make surveilling one person or hundreds of thousands of people as easy as pushing a button. There is no human scaling cost to them. That means that all it takes to abuse a massive portion of the population is one person and one action. The probability of abuse, abuse which harms a population as a whole, therefore approaches 100% no matter how 'good' the controls are on it. All mass surveillance technologies have this fundamental flaw. The consequence of that abuse is that people, rightfully, will believe that they are being watched, legitimately or not, 24/7/365. The harm here is clear. A society that is under mass surveillance is a society that is having its basic freedoms continuously attacked.

Mass surveillance, surveillance without a direct human cost that scales with the level of surveillance, is not compatible with any definition of 'freedom'. Or, to sum all this up, every argument about how a system like this could be made better to limit harm is a red herring because technologies like Flock have a fundamental flaw that is incompatible with any definition of a free society.