Fun fact: that's not true for all Windows localizations. For example, it's called "Programmi" (one word) in Italian.
Renaming system folders depending on the user's language also seems like a smart way to force developers to use dynamic references such as %ProgramFiles% instead of hard-coded paths (but some random programs will spuriously install things in "C:\Program Files" anyway).
And then half of your programs would be in "Program Files" because those people never knew windows had localizations.
The folders actually have the English name in all languages. It's just explorer.exe that uses the desktop.ini inside those folders to display a localized name. When using the CLI, you can see that.
At least it's like that since Windows 7. In windows XP, it actually used the localized names on disk.