Some people think of this as 2 years for a Masters and 2 more for PhD, but in practice most hard science programs don't really offer a true Masters program. When I got my doctorate, a bunch of us figured out we could apply to get our MS diploma after we finished our coursework -- hardly anyone in the PhD program had ever bothered before. We all got them and put them on our desks as a kind of inside joke.
Although searching Google - I can find references to the usage you're giving.
But, I fully agree that a Masters in a hard science, especially from a top research school, is almost always a consolation prize for those who drop out. My program would not accept students into the program for a Masters, it was PhD only, unless you dropped out.
My impression from talking to a lot of people, is that the European schools simply manage the PhD process to make sure it doesn't drag out too long. It's expected to be shorter, so it's shorter.
The big difference was that the PhD in the UK launched you straight into research on day 1. No teaching, no courses. He spent the first couple of years in courses, and a lot of time throughout the degree in teaching. In some ways I envied his coursework, since I was basically on my own from the start (his grad courses sounded very thorough and interesting). However I do not envy the 5 extra years it took him.
That was all a couple of decades ago now, so things may have changed.