These mutations do have a lot of spread outside of China. For example Fig. 1 of this paper (http://www.medgenetics.ru/UserFile/File/Borinskaya%202009%20...) shows a high incidence of ADH1B in the Middle East.

Is it really required that these genes are equally selective everywhere? If the adaptation theory were true, that would depend on how widely available alcohol was, as well as how harmful it is to lose the extra calories from rotting fruit, etc. No particular reason to think it would be equal everywhere.