It may sound creepy that someone is always watching, but these measures of security are there for our safety. The guards are almost always unarmed and are usually just sitting in their guard post contemplating personal matters in order to help pass the time.
China needs an extensive security system for a couple reasons, and one of them is obviously safety. The camera network for a major road or complex is extremely extensive. I once dropped my wallet on my campus while I was riding my bike and I thought that it was long gone, but all I had to do was go to the security office and let them know the situation. They were able to pull up recorded footage and pinpoint where I dropped it and follow the person who picked it up back to their dorm by switching between cameras. Another reason an extensive camera network is necessary is because of the 1.3 billion citizens the country is obligated to keep out of harm's way. It is easier to ensure the safety of your citizens if you can see what could hurt them.
This need for safety and security is being met by the camera system and the sheer force that they have with the number of people employed as security guards. Since China has 1.3 billion citizens, it has numerous employment opportunities to give people work as guards protecting other citizens.
