@nixCraft It is because before computers Americans traditionally wrote out dates in a format like January 31, 1900. Then computers came along and wanted the month expressed as numbers, so 01/31/1900.

I think most Americans can handle the YYYY-MM-DD formart without it breaking our brains but the European DD.MM.YY format just makes no sense to us. Putting the day in front of the month just seems absolutely wrong to us, in part because we have never done it that way but also if you are planning an event, in many cases the month is the first thing you want to know, then the day. But you only need to know the year if the event is more than a year away.