the 'they' here refers to US students, apologies for being unclear based on my previous sentence regarding my difficulties studying in france. fwiw i just looked it up and actually french PhDs are 3 years, so the higher level there compared to here translates directly into less time needed for a student to earn a doctoral degree.
so, in general, french undergrad > UK undergrad > US undergrad and this is reflected by students from those systems needing 3, 3.5-4, 4.5-6 years, respectively, to complete their PhDs.
i'm not saying that all US universities are bad. that is clearly not the case, as per here:
Discover the world's top universities. Explore the QS World University Rankings® 2023 based on 8 key ranking indicators.
www.topuniversities.com
see above. european doctoral programs are 3.5-4 years, and i have friends who went straight from UK PhDs to post docs in Ivy League/very highly ranked US universities and excelled. my experience and that of all academics who i've spoken to this about is that US students
in general struggle significantly when they come to study in Europe at ostensibly the same level because their studies have not given the same level of preparation. we never had any exchange students from caltech or MIT, i suspect they'd have found it a walk in the park, but they represent the very top of the US (and indeed global) university system.
conversely, the experience of academics who have taught at both US and European universities (including oxbridge, but not ivy league) is that, for the same year of study, European universities are teaching at a higher level.
we also have a large number of students coming from all over the world, even to mediocre universities. it doesn't mean anything about the level of teaching, its just that UK/US degrees are believed to be somehow better, regardless of whether the specific uni/course a student did actually was. China is realising this is dumb now and is working hard to