Visiting the Netherlands right now and every time I visit local.google.com, it reverts back to Dutch. I had no idea what the symbol on its own and only figured it out when searching how to get things back to English and seeing the symbol used in that specific context.
In don’t know that using flags for language settings is more semantic, but it’s convention so I know what it means.
I’ve seen flags used to indicate language settings for as long as I’ve been using computers.