Even though you say that yyyy-mm-dd is the ISO standard, NOBODY talks like that when they verbally say the date. When people talk dates (in English and probably other languages) they verbally say 21st of January 2006 or January 21, 2006 NOT 2006 January 21. It not only sounds backwards but it looks backwards.
My HFS, and system in general, shows the date as mm/dd/yy (1/21/06 - short date) or mm/dd/yyyy (January 21, 2006 - long date) which is what it should be for me not dd/mm/yy. (probably due to individual O/S settings in control panel).