[acidbaseextract]

For those who are into this kind of thing, here's a 25 minute mini-documentary of the US electrical system's history and problems. It's more focused on wiring, but has a lot to say on plugs: https://youtu.be/K_q-xnYRugQ

[wging]

There is a more recent video from the same person (Technology Connections) that concentrates on plugs - specifically, why US plugs have holes in them: https://www.youtube.com/watch?v=udNXMAflbU8