You are totally correct about the serious power waste, and there has been legislation passed attempting to reduce it. But still there are indeed millions of small wall warts constantly consuming power. The really simple way to prove it to yourself is to touch one that is plugged in but not supplying power. It will be warmer than the surroundings, not hot, because it is not a large amount of power being wasted and appearing as heat. And usually there is no way to switch off a device built into an outlet plate, although that is an interesting concept. Unfortunately adding a mains switch now involves an additional set of regulations, increasing the cost and the complexity.Thanks for that Bill, I had no idea transformers used juice even when they don't have load, I usually have 4 or 5 plugged in around the place for convenience as I have number of appliances that use micro USB to charge, times that by a few million people and your'e looking at some serious wattage wastage!