Chinese uses ！(Fullwidth Exclamation Mark, U+FF01) instead of ! and it is used when the user is using a Chinese input method. It becomes a hassle to use bang and search in Chinese at the same time: you need to change to English input mode (press Caps Lock or Shift), enter the !bang, change back to Chinese, enter your search, and press Enter.
(Other Asian languages like Japanese and Korea probably also applies.)
I wish ！bang can also be used as a bang search, saving a couple of precious key presses.
DuckDuckGo has this behavior, for example search for ！g query goes to https://duckduckgo.com/?q=%EF%BC%81g+query and is redirected to https://www.google.com/search?hl=en&q=query.
