(I am going to look up what Canada does.)
Hi Tim, I'm in Canada. It's a mash-up, sometimes of a very serious nature. in technical work we follow the SI spelling ("metre") for units. However because we are right next door to the USA and given their population is 10 times Canada's and there is major spill over the border of their newscasts, media, different people in Canada use both SI standard and US variants. Dates are probably the worst for ambiguity. Seeing 03-04-2020 is really ambiguous. So is that April 3, 2020? No most times the majority of Canadians mean March 4, 2020 substituting 03 for March.
That spills into data sets I see. If we are lucky and we have enough dates in a data set there will be a number larger than 12 in one of the positions in the date and from that we can figure out which system the author used, a number larger than 12 can only be "day" in that position. So 04-28-2020 and 28-04-2020 can only be April 28, 2020.
The federal government in Canada has jurisdiction over weights and measures and has official guidelines (but not that everyone follows the official guidelines) for dates writing either big to small 2020-04-03 (April 3, 2020) or small to big, 03-04-2020 for April 3, 2020. Either way is unambiguous, month is always in the middle. However I'd say the majority of Canadians put the day in the middle and we don't know what the author's preference when we acquire data. We can only examine the data looking for clues (a number larger than 12).
Time is another problem. I use the 24 hour clock in data, it's unambiguous. However you see a lot of data with 12 hour clocks and AM and PM. Worse is if the time is a text field being a mix of numbers and text. Argh.