They do. But in management of fiat currencies, it's understood that energy expenditure is an upkeep that is to be reduced. In cryptocurrencies, on the other hand, energy use is a "feature" that's intended to grow over time.

Or put differently, cryptocurrencies are trying to replace a system that's O(log n) with respect to energy with a system that's O(n^2), for questionable and mostly imaginary benefit of trustless payments.