

Spoken language is already inefficient, which is why we use so many shortcuts in it. If I’m texting someone about an upcoming event, I might also just use the day of the month or the weekday (wings on Fri?). But if I’m writing an email, signing a document, or doing something else that might be referenced weeks, months, or years in the future, ISO 8601 is the way to go.
The French, at least in Canada, put the currency symbol after the number.