I think water (assuming the brewery is competent/has decent quality control) is a big issue wrt resulting taste. Anything we drink is mostly water after all. This is the only explanation I have for why all the "Japanese" beers one can get outside of Japan taste so awful -- they're all produced on license -- and I assume the recipes are the same. Note I'm talking about industrial beers here -- so hardly the best beers in the world -- but I still think they taste markedly better if you get them in Japan. Could be a consequence of rosy memories, of course.