I speak English and live in the US. So dates in the US are not RFC 3339, they're MM/DD/YYYY drunk-endian. And units are all US Customary, not SI. If you want s

I speak English and live in the US. So dates in the US are not RFC 3339, they're MM/DD/YYYY drunk-endian. And units are all US Customary, not SI. If you want something else, you need a locale other than en.US, and if you want other things (like spell check) to match US conventions you end up needing to create a custom locale.