I can't explain why, I don't live in China. But I do notice many buildings in the cities I visit have thick strong window bars even up above the 5th floor. Maybe there is a strong concern about local petty crime?
I certainly don't disagree there is state surveillance, but I think you should be wary of assuming all devices sold in China as IoT web connected cameras are state cameras.
That is, it might be a safety measure preventing falling from a window. E.g. windows in my apartment used to have state-mandated bars because my daughter was small, and had to be prevented from falling from a window.
To be fair, I spent first 24 years of my life in China. Your idea were never appeared in any form of discussion when I was there. I did not even fancied about such explanation.
All in all, I assume you want to have a reasonable discussion.
To your point, no, those bars are not for preventing staff falling.
There are three levels of police in most jurisdictions worldwide: federal state and local. the US is no different, and putting devices on street poles typically demands compliance with planning law, and I suspect in any economy with cameras on light poles or sign posts by roads, its state actors.
The UK is either the most, or the second-most surveilled economy in the world. Not western world, worldwide. Cameras per head of population are increadibly high.
Your faith in 'old glory' is touching. I suspect, its misplaced.
Thieves will rappel down from the roof, so no floor is really safe without the bars.
Now I know: the intersection of thief, and rock-climber.