It was like that in China, but not any more - in most of the places.
We used to have lots of jokes on this too, but now there are more jokes about people talk gossips about foreigner and that foreigner just comes straight to your face and shout to you in Chinese - even in dialects
it's amazing how many foreigners speak fluent Chinese here, sometimes better than native people. I always say that Chinese is not difficult to learn at all.
so i guess it's rather hard to ask double price on "tax of lack the knowledge of the language" now.
and btw, I know some African countries are doing that for sure. My boyfriend just came back from the Victoria Waterfall some weeks ago.