I think the watchers are more trust worthy than uhhh random devices in proximity.

I would like to see a request for data be logged along with a description of an offense. An international government committee with at least 1 randomly rotated member from each foreign country each of which has the key. (there is no key inside the country) If just one deems it necessary the footage is made available to either local law enforcement, a judge or a citizen who has legitimate reason to review it. If no offense is found nothing is released. If the choice is sufficiently dubious the reviewer is reviewed and replaced. (plenty of people with eyes)

That way we can have tons of cameras without all the paranoia.