. You don't need for people not to be able to see to feel private.
No, you need for people to be not seen.
The act of watching, when it is not wanted, is a transgression against the individual. Now, you may say we've moved into a "post-individual" age, where only the collective matters, but I'm pretty sure that's not what people want. There is a basic human dignity that is violated by unwanted surveillance on people who are not suspected of crime. It's why the framers of the US Constitution made a big deal about:
The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.
It was a good idea then, and it's a much better idea now. Because when corporations and governments have the power of ubiquitous surveillance, there is no way NOT for it to be abused. Governments and corporations just don't know any better, because they are not human.
The fact that there are so many people who object to being watched should be enough. No means no. I have a right to be unwatched as much as a woman has a right to travel unmolested. If I don't want to be watched, I have a right not to be watched, when I'm in my own home, or even walking down the street.