There was this commercial on the radio about Trane heating and cooling units. The ad claimed that the units could use up to 50% less energy than your existing unit. This started me thinking (because before that I was in a complete state of non-thinking). Do you remember the Y2K problem? Basically, when people started writing programs back before Star Wars they had to be very conservative. The hardware of the time did not afford the programmers to have frivolous code. To conserve, they only used the last two digits to represent the year (1970 was represented as 70). Obviously this became a problem in 2000. So, for computers and programs, people started very conservative and the hardware became less conservative.
Now look at appliances. When people first started getting electricity in their house, it was a completely new thing. But how much electricity would a household use? At one point (I read somewhere) that it was projected that electricity could be so cheap it would be free. In this case, why make an efficient AC unit? Look at many of our energy uses today (including cars). They seem to have the legacy of being extremely inefficient.
To summarize: Computer programs start out being efficient and then go to not needing to be efficient (because computer processing is relatively cheap). Appliances start out being inefficient and are moving towards being more efficient. Really, that is all I wanted to say.