Clasen: GNOME 3.7 at the halfway mark

The "on/off" is the original English widget, that GNOME people found so cool-intuitive-and-self-explanatory they fostered it on everyone. It's based on some physical switches common on a few Anglo-Saxon locales, that were never used anywhere else because their English-only nature. (physical should have raised warning bells, software is not hardware, most physical analogies have a terrible history)

Of course during the implementation process they found the whole concept was untranslatable. Instead of revisiting the original decision, they just dumped the text labels on most locales