

In fact it was compulsory in Britain until the 1980s/90s. I’m not sure exactly when it changed, but the reason was due to different electricity companies having different sockets (and therefore plugs). It was standardised way before then, but I guess if that’s the way it has always been done nobody thinks of changing it.










This picture isn’t very clear, but I saw this similar coffee machine:
(if you can’t read it, the display says “poo”)