Regarding economies of scale - it's all so cheap that it doesn't matter for most cases that don't involve utterly tremendous amounts of resource usage.
I mean, the primary thing holding this back is consumer level ISP's being arsey about servers. A 10 year old machine hooked up to my 35mbit home connection is more than enough to run most internet services.
And that's effectively free because I already have it.
Yes, strictly. A 20W average laptop would cost approx 3-4GBP per month to leave on all the time in the UK, a modest desktop perhaps 10-15GBP.
It's been a measurement error in my power budget as far back as I can remember. Sure, you can go and compare it to EC2 or whatever if you like, but that's just silliness. It's a big mac meal.
My Threadripper box with a shitton of HDD's and RAM etc moves the needle because it has high idle consumption. I'll probably be getting rid of that soon; but it's still a low cost relative to purchase price.