In Beijing, you just have to get out of the third ring road before these are very common. The first placed I lived in was not like that, it was an older building in a fairly urban area, but after that it was a bunch of complexes (nicer apartments, it was difficult to find something nice outside of a complex), still only a few blocks away from restaurants (or a mall), but all with guarded gates.
It really shows when you want to go somewhere. You can just go from point A to point B, you can’t cut across the huge apartment complex in the middle, you have to instead go around it...that can get really annoying. Likewise, there are only a few roads that let you get between places (eg trying to go from northeast Beijing to sanlitun area, there is only one way across the airport expressway before it ends).
It does make life for pedestrians difficult.
London does have a lot more open space which is in fact privately owned, which limits your rights in that space, but that is a separate issue.
"I can’t think of any recent development that could be described as a superblock or a gated community."
Walled and gated are not the same, and smaller than superblock is probably not superblock.
My Chinese friends generally also feel safer in China than in the Western EU. What I noticed in Chengdu and Shenzhen, literally everyone walks with their nose glued to a smartphone (very frequently iPhone). Apparently robberies are not a common thing.
OTOH I've heard pick-pocketing is quite common in Beijing and Shanghai.
Shenzhen was not always that safe. Back 10 years ago, the city had unenviable reputation, but it went from one of most unsafe to one of safest.
That was done at the cost of having a police post every 100 meters (quite literally,) and it is not cheap.
Doesn't tell us much about how safe a particular city is.
gangs are prevalent just under the radar
Bicycle is fine is many not that great areas, e.g. Zhabei, Yangpu and most part of Minhang districts. Most areas within the outer ring road are fine for bicycles. Jiading is an extreme example - there are rice paddy fields just 200 meters north of the Jiading North metro station [1].
[1] satellite map here - https://map.baidu.com/@13495931.447421955,3663175.652161875,...
Except:
- bicycles can't cross the river via the tunnels, so you have to wait for a ferry to get to/from puxi/pudong (I remember this adding almost one hour to my journey one night, as the first couple of ferry terminals I visited had closed for the day, and the third had a long wait until the next ferry).
- some of the streets around the major shopping areas prohibit cyclists, even though they are open to cars and pedestrians