Hector Martin

if you consider solely point-of-sale transactions, traditional banking uses much less energy

and actually even if traditional banking uses more energy overall, it doesn't help *efficiency*

the traditional banking system can process several orders of magnitude more transactions

And ATMs do more anyway. That's dealing with physical cash. We already have cash-less centralized banking systems. Comparing Bitcoin to the cash-based economy and not the cashless economy is not a fair comparison.

similarly, points of sale worldwide consume massive amounts of power in aggregate, but that'd be true regardless of the payment system used

Bitcoin points of sale (real ones participating in the network) would use way more energy than traditional ones anyway. You can't run bitcoind on a tiny embedded platform with megabytes of storage.

yes you can. There are thousand of raspberry pi 3 bitcoin nodes right now. and many lightning nodes at the same hardware that can handle 10x transactions than the traditional banking system. I dont know any bank to run in a system like this

You don't seem to understand the concept of "megabyte". I'm talking about things like POS terminals, which have much, much smaller CPUs than a Raspberry Pi, much less RAM and storage. And Lightning cannot handle the transaction volume of traditional banking, not even close.