Why are outside lights ...

[Uwe S.]

... on apartment building and houses always turned on?
I look many times to Google Streetview and I saw all times, outside lights are on.
Why? Is this a law or so?
Who need outside lights on day? Thats big waste of energy if this a rule in entire US.

-Uwe

[Steve Babiak]

I am aware that on the inside, it is because the lawyers advise that a dark area is a liability. Perhaps this same concept is being extended to the outdoors.

Any lighting that illuminates a sign will be on as part of the advertising of the place.