@jdaviescoates I'm just using the terms that were in the post. "A single Bitcoin transaction...", "iPhone ... process more transactions". Both transactions are on the blockchain. Perhaps the first statement was trying to say something more like "ALL the computers connected to the blockchain when a transaction occurs use more energy than...". The first statement sounds like an exaggeration and frankly won't sway most away from using Bitcoin (well, any phrase always has the potential to sway some number of people any which way). It wouldn't be accurate to say that ALL computers connected to the blockchain are essential for any given transaction to process, but that is what is implied. It isn't true. It certainly is fine and good for people to make others aware that there are costs associated with Bitcoin, but I'd avoid fearmongering.
I thought I'd brush up my info before posting, and read https://river.com/learn/how-does-a-bitcoin-transaction-work/. So, yeah, I can't confirm how much energy a given mining NODE uses to mine a specific order, but it still looks to me like fearmongering when the costs are talked about, generally.