If people would just slow down in residential neighborhoods there probably wouldn't be any need to draw attention to the problem by placing objects in the streets.
This is truth right here. ^^^^^ The jackholes that complain about these signs are the same ones who usually are speeding through the neighborhood and are the reason the residence put them out in the first place. IMO, there is no reasonable explanation for two cars to get into an accident because of this sign if the two drivers are halfway competent and are driving the speed limit and are using a modicum of good sense.