Buying an hour of fire feels quantitatively different from buying an hour of light. When I go camping, my solar-fed LED lanterns are plenty bright, but I still need to cook and stay warm. I can do that using heat, which the efficient lights cannot produce in sufficient quantities.
Ever tried an infrared lightbulb? (They often put them in bathrooms as something you can turn on after you shower to dry the bathroom out more quickly, usually in combination with a vent fan.)