There’s an old email meme that you still see from time to time about how ancient Roman roads determined the width of modern railroads. Snopes tells us that it’s not terribly accurate, but the moral is clear enough: precedents are hard to shake.
Some patterns, like which side of the road you drive on, are very coercive. In such cases, once a local pattern is established, it’s dangerous or impossible to oppose it. What’s interesting is when these local patterns grow from small seeds into a global mosaic. Coercive growth of left-side driving, for example, propagated through much of the British Empire. But frontiers between differing regions are interesting places. What happens when you drive your car from a left-driving country to a right-driving country? In some cases (like Sweden in 1967) the resulting friction is enough to make the whole country switch. But in general, the cement has hardened, and everybody just has to live with the tension between two standards.
Electrical plugs are good examples of this. The standards are coercive, and when they harden, there’s not much you can do after that. Here’s a good article on Gizmodo about Why Every Country Has a Different F#$%ing Plug.
There’s a nice bit in there about how the UK came up with a new plug design after World War II. It seemed like a reasonable time to try something new, and the UK had a whole empire to foist it on after all. So you can see why they felt a certain sense of entitlement. But their timing was, in fact, terrible. They acted at the very moment the empire was going to pieces, and the legacy is an electrical plug that works (almost) nowhere else in the world. Still, what a manly hunk of metal is the English plug! It certainly shames the effete French two-pronger across the Channel.
Rambles Blog at Star Chamber 
Thank God the English weren’t in charge of developing USB! It’s embarrassing enough to have a wall plug larger than most portable electronic devices, imaging the tower cases if they’d done the same for serial ports.
Oh, and Happy Beethoven’s Birthday!
Beethoven thanks you for the birthday wishes, I feel certain. I wonder if they had problems with standard candlestick sizes in Vienna back in the day. “Lieber Gott! I told you to get the 20-gauge candles. The show starts in ten minutes, und my candelabra ist kaputt!”
“Perhaps, Herr Beethoven, we can just perform your new sonata in the moonlight…”
When we went to India, I was amazed at how infrequently we had to use a plug adapter. At hotels where we stayed, most plugs accepted most (if not all) of the standard plug configurations and shapes. Combine that with the fact that most AC/DC converter bricks handle 110 & 220V, and the world seems a lot more sane.
I’ve heard that the British plugs are so manly because they include a fuse in the plug itself. Personally, I think the American plugs are the flimsiest around.