Update: This occurs on almost every car. I have seen videos of everything from Maximas to little foreign cheap cars in videos crashing and having their wipers go on. In the new Batman movie the Murcielago he was driving had the wipers go on when he got in a little side impact accident. read more
The simple answer is that they don't. Sometimes movement people in the car, inflating "airbags" move the wipers' switch, but it is far from common. read more