All of them acknowledge difficulty in computation. It's like trying to solve the drake equation. Unless you know all the terms in the equation accurately the number at the end isn't terribly useful.

Many different computations seem to be in same order of magnitude.

The result of high energy consumption is unsurprising and intuitive, given the design principal of PoW. It's all about who is prepared to do the most work, up until economic limits set by current BTC rate.