I am surprised to find Java's Locale.ROOT is not American.
DateFormat dateFormat = DateFormat.getDateInstance(DateFormat.DEFAULT, Locale.ROOT);
System.out.println(dateFormat.format(new Date()));
dateFormat = DateFormat.getTimeInstance(DateFormat.DEFAULT, Locale.ROOT);
System.out.println(dateFormat.format(new Date()));
NumberFormat numberFormatter = NumberFormat.getNumberInstance(Locale.ROOT);
System.out.println(numberFormatter.format(12.34));
NumberFormat currencyFormatter = NumberFormat.getCurrencyInstance(Locale.ROOT);
System.out.println(currencyFormatter.format(12.34));
2025 Oct 13
10:12:42
12.34
¤ 12.34
Even POSIX C is less American than I expected, with a metric paper size and no currency symbol defined (¤ isn't in ASCII). Only the American date format.