If people all import their vehicles from Japan instead of buying from the local supply chain, that hurts their international operations considerably. In turn, that costs jobs here in Australia and everywhere else. What seems like a simple language change to you or I, really becomes a problem for all concerned along the line. So, manufacturers of various products have their domestic product and support it domestically only.
As Ben said, when that Japanese domestic product leaves their shores, it's really not their problem any longer. It's not like you had any business with them if you were to never buy another secondhand Nissan ever again. Would it be nice if Nissan had multiple selectable languages in these systems? Sure. Would it be feasible? Definitely. Would it actually be used in a country whose 99.9% proportion of users are Japanese? Not likely, so they don't bother and that's fair enough.
When I bought my V36, I knew this was going to be an issue and I worked out my own Infotainment system to augment it. Time to get creative and/or resourceful, dude.