As a brit I'd say we tend to use "en-dashes", slightly shorter versions - so more similar to a hyphen and so often typed like that - with spaces either side.

I never saw em-dashes—the longer version with no space—outside of published books and now AI.

The en-dash is also highly worthy!

Just to say, though, we em-dashers do have pre-GPT receipts:

https://news.ycombinator.com/item?id=46673869

Besides the LaTeX use, on Linux if you have gone into your keyboard options and configured a rarely-used key to be your Compose key (I like to use the "menu" key for this purpose, or right Alt if on a keyboard with no "menu" key), you can type Compose sequences as follows (note how they closely resemble the LaTeX -- or --- sequences):

Compose, hyphen, hyphen, period: produces – (en dash) Compose, hyphen, hyphen, hyphen: produces — (em dash)

And many other useful sequences too, like Compose, lowercase o, lowercase o to produce the ° (degree) symbol. If you're running Linux, look into your keyboard settings and dig into the advanced settings until you find the Compose key, it's super handy.

P.S. If I was running Windows I would probably never type em dashes. But since the key combination to type them on Linux is so easy to remember, I use em dashes, degree symbols, and other things all the time.

I think that's just incorrect. There are varying conventions for spaces vs no spaces around em dashes, but all English manuals of style confine to en dashes just to things like "0–10" and "Louisville–Calgary" — at least to my knowledge.

It's also easy to get them in LaTeX: just type --- and they will appear as an em-dash in your output.

Came here to confirm this. I grew up learning BrE and indeed in BrE, we were taught to use en-dash. I don't think we were ever taught em-dash at all. My first encounter with em-dash was with LaTeX's '---' as an adult.