Could this be where the 550 m setback came from?

There is no scientific consensus on a safe setback distance between residences & wind turbines. Perhaps Ontario’s 550 m setback has more to do with assuring developers that a turbine can be dropped at the back of each rural lot, as indicated by the orange area below. If the adult residents have signed a lease with the wind company, then the turbine can be placed in the yellow area as well.