In private dealings 100% of the time is acceptable as that is a matter of property rights. If someone chooses to monitor their home or business that is their business, except for perhaps in restrooms or other facilities where people have a reasonable expectation of privacy. In the public sphere however, I think the government should have to demonstrate some need determined by set standards before they can monitor an area with cameras. Examples might be areas known to have problems with drug dealing or prostitution or intersections known for particularly hazardous traffic. The police would go before a panel of citizens and say, ‘we are having a problem with “x” at the intersection or 5th and Pine and we’d like to install four cameras at the location.’ Then the panel would review the request and either grant it or deny it. The panel should either be randomly chosen like jurists or elected by the community.
That sounds fairly reasonable. The WA state police didn’t meet your criteria and I think they should be required to do so