I can't agree with this, because many times while driving home I will encounter a patrol car from Sengkang NPP. So I have to guai guai drive at 60km/h...
As for reaction time, I recall there were 2 incidents that happened near my place. In both cases the first patrol car arrived in < 5 mins.
Hmmm... there were 2 incidents (not accident) when my friend in Punggol called for police help... patrol only arrived at an average 25mins later, despite calling 2 times during each incident.
Maybe it is the timing, my friend's incidents happened quite late at night.