I'm only very quickly going to highlight the use of the word 'Staff'.
Staff are civilians who (in Scotland) do not hold the office of Constable. I.e, could be a temp from a job agency for example. Most corruption issues around data happen through Staff, not Officers. Partly down to the training, partly down to the cop being far more aware of how wrong it is and what the risks are.
So it's not necessarily all cops, and often from my experience, it is the civilian staff.
Also, not sure about England but in Scotland,you hold the office of Constable and as such, are on duty at all times, though of course you only get paid for your working hours!
I could be done with neglect of duty (as has happened to others) if I ignore something whilst off duty, that's what the role confers on me - a responsibility to my community and the public at all times. As such, I can arrest at any time, uniform or not.
But back to topic, mainly staff not cops.