UK surveillance is very high, and increasing, furthermore, it is quite often active via automated software, not necessarily a person. But still identifes you, your vehicle, address via DVLA, etc etc." for our records just in case". I've seen it in use and was very impressed by it's accuracy, speed, and abilities (e.g. ID by body shape/movement gait). Even id'd & recorded the local fox and cat!
Most towns now have town centre/shopping centre CCTV to combat shoplifting , crime and youth disturbance ( the last a growing problem in many areas).
In the park apple slicing scenario, it is now more than likely than not, at least in the south, that a member of the public will nervously make a call/video and you'll have some form of enforcement arrive before you've finished the apple! I do use mine at lunchtime in public if necessary, but am pretty careful who is around and don't leave it out in plain sight.