I reckon we should have a 'light' tax. And you get 'light' credits if you use candles at home.
Seriously that won't go away unless penalties or money are involved.
Residential area don't seem to account for much of LP compared to Industrial zoning, in the west anyway. If you jack power pricing right up the cost will be passed to the consumers in the end so that wouldn't work at all.
I don't know of any pollie who would have the balls to pass a legislation to switch the lights off or 90% of them in non critical areas such as industrial areas at night but that's where it would/should start.
Maybe financial incentive to turn them off? Tax cuts? I'm dreaming aloud here.