I don't think this was just a sovcit thing, I have always been told to do this and do so if practical. Cop flicks lights on, pull into plaza parking lot and park. Safer for the police as they are not on the street, they usually will pull behind you so they know you won't be able to back out to run. If they arrest you, most restaurants, grocery stores, etc won't tow your car if you leave it overnight.

Also smart to turn on the overhead light, turn music down/off and put your hands on the steering wheel so they can see exactly where they are.