(The small fraud problem is one reason I think micro payments can't happen: you can't investigate sub-cent fraud, but if someone can automate it they can steal a lot.)
We already have costs built into the current system (e.g. cc fees to make up for fraud, security systems around protecting gold + cash). Electricity is just the cost of that specific system - I think calling it a waste is not necessarily justified.
In the EU where people don't want the system to work like that interchange fees were capped in 2015 at 0.2% for debit and 0.3% for credit [1]. If that's what you want, there's a proven model for establishing it. In Australia it's capped at 0.88% for credit and the greater of 16.5c or 0.22% on debit [2].
Did you know Bitcoin alone ALREADY used 0.5% of world electricity at the end of 2018, even though nobody really uses it? [3] It's like we're all paying a 0.5% surcharge on top of everything we do, which is double the price of EU interchange. Just to support some ancap pyramid scheme that people agree solves largely 1 class of problem: payments for illegal goods and services, while pretending to solve all the worlds problems, just poorly.
[1] https://www.adyen.com/blog/all-you-need-to-know-about-the-eu...
[2] https://www.adyen.com/blog/card-processing-in-australia-just...
[3] https://www.sciencedaily.com/releases/2018/05/180516131236.h...
It happens to be that the EU is such a "someone". In EU countries, CC interchange fees are limited to 0,3%, debit fees to 0,2%, effectively resulting in much cheaper rates to be paid by merchants (whether big or small) for card acceptance.
Thoughtful legislation and an effective, fair and trusted executive branch, both with the necessary checks and balances, trump any blockchain, at least as long as we are talking about legal transactions.