In Britain the standard way to write a date has always been, e.g "12th March 2023” or 12/3/2023 for short. Don't think there's a standard for where to put the time, though, I can imagine it both before and after.

Doing numbers little-endian does make more sense. It's weird that we switch to RTL when doing arithmetic. Amusingly the Wikipedia page for Hindu-Arabic numeral system claims that their RTL scripts switch to LTR for numbers. Nope... the inventors of our numeral system used little-endian and we forgot to reverse it for our LTR scripts...

Edit: I had to pull out Knuth here (vol. 2). So apparently the original Hindu scripts were LTR, like Latin, and Arabic is RTL. According to Knuth the earliest known Hindu manuscripts have the numbers "backwards", meaning most significant digit at the right, but soon switched to most significant at the left. So I read that as starting in little-endian but switching to big-endian.

These were later translated to Arabic (RTL), but the order of writing numbers remained the same, so became little-endian ("backwards").

Later still the numerals were introduced into Latin but, again, the order remained the same, so becoming big-endian again.