It is? I've only ever seen dd/mm/yyyy or dd/mm/yy as standard date format, with different separators instead of / depending on the country.
It isn't used on any official forms and such that I'm aware of, at least outside technical circles, but people don't tend to have a problem with YMD ordered formats when they are used.
Sweden used YYYY-MM-DD before ISO 8601 was even written, and many other countries use it too.
I know at least some countries further East used it as a matter of course, but I wasn't aware any countries in/near Europe did.