I believe most people in Europe use a localized ISO layout.

Except Romania, where 99% of people use US QWERTY due to a very particular set of circumstances:

• Romanian has very few diacritics and it can be 99% understood (in writing) even if you omit them completely. So most of the time people don't bother to use diacritics for digital communication.
• After the 1989 Revolution when it rejoined the modern world the Government took about a decade to make up and push standards for the Romanian language in IT (a history of all the fuckups is here if you're curious). Localized ISO layout and Romanian keyboards were eventually created but they never quite took off...
• ...last but not the least because a simpler layout has become the de facto standard (diacritics on 3rd and 4th level, activated with the right-hand Alt). It's simple, intuitive, easy to learn, and you can use it with any US keyboard.