I don't believe any of your suggestions are true in a way that don't apply to public spaces in general. I wouldn't do "thing x" in case the wrong people saw, but that includes the possibility of a friend of my boss seeing me making out with his wife so I'm not going to do that where I might be seen.
Claiming that surveillance is bad because oppression is bad is a Strawman. It's the process of taking any position (the GP stating public cameras are fine) and then introducing your own version of his claim (Cameras=Oppression) and then arguing against oppression.
>"They" have already done that over and over in analogous historical situations.
This argument sits in the box with my father who was eternally upset because we didn't have the military to fight a war and we'd regret that because ~World War 3~. He may indeed end up being right, but to pretend that nuclear proliferation hasn't changed the face of war seems ludicrous to me.