A note from the front line. I actually use 8601 dates in a date-heavy consumer product ( https://clubman.app ) and it’s hands down the feature I most consistently get user feedback on.

It’s always “Why are the dates all American format? Can you change them to English?” And then I try to patiently explain that they’re actually international format.

People seem to have internalised that any date format they find slightly unfamiliar is “the bad American one”

I’m in the process of cutting everything I can over to “24th Jan 2020” style.