[throwaway160303]

So. You want prevent, through the use of force and the rule of law, private citizens from taking photographs of people in public places and comparing those photographs with a voluntarily provided corpus?

Enforcing such rules would take nothing short of a totalitarian state.

There was no privacy when we lived in villages, and we will return to that state in the mid-term future. The anonymity of the modern metropolis and the accompanying sensation of privacy in our day-to-day lives is but a temporary aberration in the history of the human experience.

Do not get used to it. It is not long for this world.

[thingification]

Can you explain why it's necessary to prevent people doing those things, or to impose a totalitarian state, in order to prevent identification of random citizen x by random citizen y?

It seems what's actually needed to prevent that is controls on the creation and use of large databases in order to identify faces (except under some list of acceptable uses). People who work in IT often express disbelief that laws like that could work. In fact, factors that humans understand like scale and intent are an important part of law, and laws written in those terms are commonplace.

Re villages: another thing commonplace in the past was brutal violence. In the past, it was obvious that brutal violence was inevitable. Then, we made it illegal, and it largely stopped. We should do that again, in this case.