Okay, I do agree with you on what I previously described as a "trade-off between lives and money." I didn't mean it in that sense - I was just trying to illustrate that if you saw it as two separate measurements, you could see it as a trade-off instead, meaning they are interrelated.
Looked up Big-O on Wikipedia, and it seems simple enough. I also agree on that efficiency is not easy to put a blanket statement on. However, as something intangible, it is a result of the best possible outcome given every single detail is given a weight and value. I think that is where human creativity is the most valuable. Automation and the right information help to aid with information-gathering, which would bias us otherwise. There may be even higher levels of thinking than what our brains can fathom (eg, entities who live in 4D, if they even exist), and factors in efficiency can be part of that. However, we still know what the outcome is (ie, it took me 1.5 seconds to make this widget versus 2.0 seconds), given a constant input (technology), and that makes it the simplest to understand efficiency.
To be honest, I think this is all just bundled up in layers, and we can only understand a certain tier. Like AI can only understand layers up to right below humans, because we made them. Or how we can only visualize 3D and most AI in 2. Just like how a system can be inefficient/efficient, and if we are really inefficient/efficient. And if there is another level beyond the system that can be inefficient/efficient.
And ya, I know you were teasing. I respond to all things, anyway XD