There is a moral, albeit not a legal difference, between driving along watching Netflix (or doing anything with your phone whilst moving/ driving), and checking message etc whilst stationary at a set of lights etc. Both are illegal, the latter is is multiples more dangerous. Very few people have been injured by a stationery car.
whilst i wouldn't advocate using your phone at al whilst in the car, I certainly wouldn't advocate tying to "poice" mobile use, in a stationery queu of vehicles.
Twunts driving along with a phone in one had engrossed it in however, are fair game...