[ben_w]

Green500 top supercomputer, gets 65Gflops/W.

65Gflops/W = 6.5e10 operations per joule = 2.34×10^17 per kWh

Assume $0.05/kWh electricity: (2.34×10^17 operations/kWh) / ($0.05/kWh) = 4.68×10^18 operations per US dollar

Human brain computational estimates are all over the place, but one from ages ago is 36.8×10^15 flops ≈ 3.7e16 operations/second ≈ 1.3e20 operations/hour: https://hplusmagazine.com/2009/04/07/brain-chip/

Given previously calculated cost, this is equivalent to a human that costs $28.31/hour.

Of course, as we haven't actually done this yet, we don't know if that computational estimate is correct, nor if we do or don't need to give it off-hours and holidays.

Still, general explanation is there's a lot of room for improvement when it comes to energy efficiently in computation; calling this Moore's Law may be inaccurate, but the reality happens to have rhymed thus far.