To me it always seemed wrong OS vendors support and encourage hundreds of "locales" instead of pushing the international standards like this into wider adoption. So far there even is no international locale option and, except on Windows, no easy way to tweak your locale.
Living in the EU I still use the US locale for apps and libs to work the default way, except on Windows (where this has always been easy) I have always been manually tweaking it to use the metric system and the ISO date and time format. The only annoyance in this case is printing apps defaulting to Letter rather than A4 paper, using national locales causes much more annoyances.