I have said that if you are caught by a police vehicle the officer would pull you over and issue a ticket
The other's argument is that the infringement would be recorded on camera and dealt with the same as any other cctv / speed camera etc
Both arguments are correct. You can be stopped and reported at the time. Or the officer can note the time, date and offence location plus the vehicle details and come round to your house and report you there. Or the infringement is recorded on camera and he tracks you down and reports you using the camera as evidence if required. As also stated, if he is off duty and sees an offence, he can when on duty call and see you and report you. Ideally he would need some extra evidence to ensure a conviction.