In Europe some countries still use XML as the official data format and XSLT as the official code format.

It's used a lot in the publishing industry, which stores the content in JATS and other similar XML markup. It's also used by the US government for bills, etc.

Typically, these use XSLT on the backend to transform the content to HTML to be sent to the web browser.

And there's RSS which was mentioned in the previous discussions. Podcasts will typically have HTML renderings of that data, but if you opened the RSS in a web browser you could use XSLT to provide a user-friendly view of the content.

XSLT can also be used to provide fallback rendering for unsupported content, such as converting MathML to HTML for browsers without support. -- Chrome as of 109 supports MathML Core, but doesn't support the content markup (used for more semantic markup of common constructs like N-ary sum, integrals, etc.), so would still need something like XSLT to convert that markup to the presentation markup supported by Chrome.

Not just "still use", at least here in Germany our brand new e-invoicing system (mandatory since this year) is built on XML.

And XSL is used to validate invoice documents.

It's not only in Germany, it's an EU mandated thing to have e-invoicing to prevent fraud and whatever other things the bureaucrats in Brussels felt like it would be solved with technology.

And yes, sadly the powers that be decided that this crap needs to be XML. Because why not, why use a modern standard...

What about XML isn't modern? It's a far more capable format than JSON or anything else you can devise.

How about we agree to disagree? XML has no place in the modern world. If it wouldn't be for the likes of Microsoft, IBM, Oracle and a few others that keep using it and pushing it, it would have sailed into the sunset a long time ago.