But you are forgetting one key point. Any report takes about 4 minutes to propagate across the network, so such a report is worthless. Do Not report moving police. By the time anyone else sees your report, the officer is likely miles away in who knows what direction, from the point of the report.
The time to propagate is limited due to Waze trying to not overload peoples data connections. And the delay is also there as a privacy protection matter. Waze also delays how quickly a report appears to give a degree of privacy to it's users. What if that officer doesn't like waze and notes the blue subaru with the cell phone mounted on it's dash, and the driver tapped the phone a couple times and then the officer's location popped up on his waze screen, is that couple taps on the device going to violate the state's no texting laws? It's not an easy fix, and it's not a logical addition. A moving officer inserts too many variables to be able to predict his location for more than a few seconds. Or do you propose allowing users to repeatedly post about the officer they are following thus increasing the amount of spam rather than decreasing it, and further distracting those drivers making such posts.
It sounds like a good idea but it is not. There is NO value in reporting a moving police car. You don't know if he's cruising to show a presence, moving to a site to set up a radar trap, heading back to the office, heading to eat, heading home etc. A moving police car is not a hazard to navigation. Further; avoiding tickets is NOT the primary reason for these reports, even if it is reported as a speed trap, the real reason is to warn of the hazard created by the officer sitting on the side of the road.
What good does reporting the lane do, when 2 seconds after you hit send, he changes lanes? Then twenty seconds later he's off at the next off ramp? Your report is now more worthless than the frequent posts as he bounces down the road from speeder to speeder where he is usually going to be sitting for 10-15 minutes at a time.
But again all of you posting what a great idea this is are ignoring the fact that the moment you hit send the report is sent, four minutes will pass before anyone else sees it, but even if waze manages to cut it down to 10 seconds, the instant you post it it's set on the map, and 2 seconds later the officer changes direction speed or lane and your post is worthless. If you are six miles away from an "in motion" police, unless he's just circling the same area you will most likely never see him, unless your overtake speed is so high that you deserve to get a ticket as you are a hazard to others.
Stationary police reports are often incorrect by the time they propagate across the network, and you somehow think moving reports would be an improvement?