I think it primarily depends on whether a person has a right to expect privacy in the particular situation. We may not like cameras in all kinds of public places, but I don't think we have the expectation of privacy at the local shopping mall or bank. It's reasonable to expect privacy somewhere like (even) public restrooms, so that would certainly be a violation.
I think in a place where people have the reasonable expectation of privacy (maybe a babysitter in someone else's home) it would be a violation if the babysitter were not informed there were cameras. The other part to that, though, is that I don't think, in someone else's home and being paid by those people, the babysitter has a right to expect the same privacy she could expect in her own home. I think the difference between the babysitter and someone working at a company is a combination of her assuming there would be privacy in a home, as well as the more personal nature of her relationship with the parents.
I think most of us just kind of know there are cameras "everywhere" in public; but one thing I do think is a violation of a person's privacy in public is when someone that person would not expect to be taking their picture uses something like a cell phone camera to take their picture. We expect businesses to have cameras and legitimate reasons for having them. We don't expect fellow citizens to be taking our pictures or to have good reason for doing so.