I think the concern is that humans have very poor track record of defining efficiency let alone implementing solutions that serve it.

The equilibrium of ecology, without human interference, could be considered perfect efficiency. It's only when we get in there with our theories about mass production and consumption that we muss it up. We seem to forget that our well-being isn't self-determined, but dependent on the environment. But, like George Carlin said, "the Earth isn't going anywhere...WE ARE!"

It's quite telling how much faith you put in humanity though, you sound fully bought in.