Similar for many other aspects of life. If you see someone driving like a Fkwit, do you pull up at the next traffic lights and inform them of the dangers of their actions? And if so, is your advice taken positively?
Depends on whether you're going to get your head beaten-in car smashed up. But remember: if you do nothing, that idiot might kill your missus or daughter/son.
I don't have any compunction blasting some moron who is on their phone, foot still firmly on the brake, when everybody has gone on a green light. D!ickheads. Just maybe they'll think twice next time before tapping when they should be looking out, avoiding an accident.