I'm half joking. We are writing numbers in big-endian in all the discussed formats (euro, american, iso) so I do think it makes sense to store dates in big endian to maintain consistency with that and lists and such. Otherwise people can do whatever makes sense culturally to them. Americans also write today's date like 4/7/2025 which is obviously middle endian lol
... in English, anyway. A lot of languages are little-endian both for dates and for at least 2-digit numbers, if not larger numbers.
(Just in case your post isn't a joke.)