Of course energy efficiency is not the only, or even primary reason. But it is there somewhere, and insofar as it isn’t (would people be willing to pay for 4x the energy use? 8x? 16x?) it is just evidence that energy is too cheap if people don’t need to think about it!

I do grant you that energy efficiency wins in many fixed appliances (washing machines, fridges, etc) do probably transfer directly to reduced energy usage by those appliances – but remember that energy is fungible, and reduced use here may and often will transfer to increased use there.