Natural gas is a resource that can not be digitally copied, and you may think electricity comes from vapor but I can assure you it costs money to produce it unless you have your own solar panels and are off the grid.<p>And its not necessarily a matter of enforcability as it is <i>availability</i>. If natural gas and electricity were as easy to steal as computer games or WiFi then people would do it. Natural gas and electricity, while commodities, are still limited by our technology and can not be given to everyone with a computer as easily as computer games.