Streetlights can also be turned on with 'this inflame true'
It is not only for fires.
As UnNamed said they do tend to flicker a little.
Try the streetlights that came with CWC.
From the Command Reference:
lamppost switchLight mode
Operand types:
lamppost: Object
mode: String
Type of returned value:
Nothing
Description:
Controls lamppost mode. Mode may be "ON", "OFF", "AUTO". "AUTO" is default, lampost is on only during night time.
Example:
nearestObject [player, "StreetLamp"] switchLight "Off"
Example:
object 159582 switchlight "on"
Planck