Well, you may call it surveillance cams but it may not be a bad thing. But as a Chinese, I never feel stressful under these cams in China, but feel unsafe all the time walking down the street in SF in the night after moving to US.
Purpose matters.
Purpose matters.
The point about many of these privacy related issues is that purpose can change.
Almost nobody is arguing that it's not a good goal to feel safe on the streets. But there can be an argument made that cameras don't actually increase safety (though they can increase the illusion of safety) and the more important point: Increased safety is only one purpose of many of these cameras. Even if it is the only one right now, all it takes is a shift in political climate, and suddenly they can be used for many other things without, and this is the important bit, changing anything about the cameras themselves.
To take up your example of being feeling safe as a Chinese in China (but don't misunderstand me, this is exactly the same in any other country!) probably works because you are not interesting to the people controlling the cameras (and the other surveillance ). But once you aren't aligned with their interests anymore and you start making trouble, these cameras give your opponents tremendous power over you.
Privacy doesn't matter if you are aligned with those in power. The power imbalance it perpetuates only starts mattering as you move away from the center of society.
Maybe public surveillance camera help preventing armed attacks (but it's never really been a thing in China anyway, and in serious decline in the world in general) and I doubt they can do much more. As you say, purpose matters.
I don't believe crime stops with surveillance, it changes.
Edit: one thing I forgot to mention, I feel the Chinese state media are doing a very good job at not talking too much about the different crime/problems happening. Western media are doing pretty much the opposite. I think on that precise point, if other method than censorship were used, it's actually a pretty good thing and do make people feel safer.
In China, I had a traffic altercation (between me, a pedestrian, and some people who were in a car at the time the altercation started). The police found the video footage and watched it within an hour after I reported it.
My point: the plural of anecdote is not data.
So I suspect violence is affected much more by culture/policy than cameras. Surely cameras may help, but for them to work one already needs a functional society. For example, cameras do not work when one can bribe police/courts to remove/ignore video evidence, like it happens in Russia.
I think one interesting thing I saw at GTC two years ago, was a Chinese firm was building software to watch / track where everyone went through a city. Including what they were doing. This is not a "safety tool" it's a surveillance tool. Sure it can be used to _maybe_ track down attackers after it happens. However, it can be used more effectively to track potential or known dissidents or track what the average person in the population is doing.
[1] http://www.independent.co.uk/news/business/news/china-billio...
[2] https://thediplomat.com/2016/06/china-the-us-and-extrajudici...
[3] https://www.theguardian.com/world/2016/jun/17/china-behaving...
for crime it's great, but if you're a dissident they also know where you've been, or hackers can sell your schedule to unscrupulous people if it's not secure.