Another recent example - I had to fight for two hours with yet another javascript date/time picker to present date in localizaiton of a browser. Turns out this popular picker didn't have proper support for localization and set US one by default.
The same issue I had with Flutter time picker, btw. Not sure if it's been fixed by now, but making proper localization support can be quite challenging even in 2022.
Sure, localization support is getting better each decade, but it's far from perfect. And if you've used software since 1986, then you should remember that at that time the concept of localization DIDN'T EVEN EXIST and majority of the software (including DOS!) used US format (there were "localized" versions of DOS, ofc, but those were even branded differently and the best you could get is codepage, keyboard and printer support).
I've been using computers since 1986, and I've used many many software packages.
Which software package uses month-day-year outside of the US? Every package uses the locale, so the 94% of the population outside of the US literally never sees this format.