That AC example is exactly what I’m talking about in term of side effect. I bought my AC a few years ago and my AC system is SEER-16 and my heater is 98% efficient. I have the $ to front the cost difference banking on the energy saving in the long run. However, not everyone can afford to spend a few more grand up front. Which mean those people would have to live w/out AC or upgrade to 92% efficient unit if their old unit is @ <80%, if we put a limit at 95% efficiency.
As for incandescent vs LED, that's another horrible example. W/ incandescent, each bulb is a few cents while LED, each bulb is a couple of $. How long would you have to use those incandescent before it break event w/ LED? My outdoor light gets used maybe 1 hour a month on average. How long do you think it'll take to break even? There nothing wrong w/ LED, but not everyone can afford it and it's not the right solution in all situation.