Being Swedish I totally agree with XKCD since that's how dates are written here since the 70's.
But this standard seems to be receding, for example recently the Swedish DMV had to change so that on new driver's licenses the date is written '01.01.1984' instead of previously '1984-01-01' :-( because of EU parliament rules.
Nitpick: the example was '1984.01.01' whereas the ISO format is from 1988. The ante-ISO form of representing dates may therefore be intentional, as a game design detail.