What about clouds? Lights that only work x% of the time isn't that useful, they'll still need to maintain all standard infrastructure which will surely wipe out the potential savings.

Plus the existing huge debt burden that we're starting to learn about, I doubt the central gov would greenlight this in front of on-the-ground problems.

Clouds would definitely lower the amount of light coming through, but a cloudy full moon night is still much brighter than a clear night with a new moon. (note this does not mean I think this 'artificial moon' is a good idea)