Every windows install I've ever done (in Australia) I picked "English (Australia)" when possible, and "English (UK)" before Microsoft provided that localisation option. I've never seen US letter as a default.

That's funny because (living in the US) I've noticed that many printers default to A4. Maybe 20 years ago, one printer at work would think A4 paper was loaded in it after every power-failure and we'd have to go through the menu and change it, or it would require you to clear a warning before it would print anything sized for US letter.

Must be an Anglosphere thing. Every non-English computer and office software I've ever used correctly defaulted to A4.

Like most of your standards. No-one knows why, but it's obviously advantageous to defend it religiously as "better than everyone else"

That Wikipedia article was lacking citations so I dug some up with ChatGPT: https://www.govinfo.gov/content/pkg/GPO-CPUB-101spub9/pdf/GP...

On page 52 (57 of the PDF), there’s a letter dated December 18th 1978 (Carter administration, not Reagan) from the Congressional Joint Committee on Printing adopting 8.5”x11”, effective January 1st 1980 so departments & agencies could use up their 8.5”x10.5” stock.

I also found this article from Time from January 15th 1979 that this was actually slightly cheaper despite using more paper: https://content.time.com/time/subscriber/article/0%2C33009%2...

The government adopted 8.5”x10.5” to save money back in 1921 vs what was already the industry standard of 8.5”x11”, but this ended up backfiring and a General Services Administration report in 1972 recommended switching to 8.5”x11” would reduce by 5% the amount of times a secretary would need a second page. The Joint Committee of Printing estimated this change would save several million dollars.

> On hearing the news, one straight-faced bureaucrat in the Government Printing Office said of his colleagues' reaction to the news: "Some people think that this issue has been inadequately studied."

Apparently the American Forest & Paper Association is under the impression that it was the Reagan administration’s proclamation:

> Oddly enough, the United States used two different sizes - the 8" x 10.5" and the 8.5" x 11". Separate committees came up with separate standards, the 8" x 10.5" for the government and the 8.5" x 11" for the rest of us. Once these committees found out about each other a couple years later, they agreed to disagree until the early 1980's when Reagan finally proclaimed that the 8.5" x 11" was the official standard sized paper.

https://web.archive.org/web/20120220192919/http://www.afandp...

Or "legal".