After working at several universities, and interacting with lots of institutions on both sides of the pond, I think this freedom issue is also what makes American Academia more successful than European Academia these days.
In Europe, academic freedom is limited because the structure we have resembles a very wide pyramid, with some minor differences across fields and countries. Junior professorships are more rare and more difficult to get into. The result is always the same, a full professor that controls his field locally and lots of expendable badly-paid postdocs working for him. Access to funding is also much more limited, which in turn restricts the capacity of said postdocs to pursue their own ideas, even while working under the umbrella of the professor.
In the US, tenure-track assistant professorships are much more common and requirements to apply are more flexible. Seed grants for junior faculty members are also common and not too hard to obtain. The result is a lot more freedom to explore. Basically, it is the same issue as with technology. EU suffers from over-regulation and control by some rent-seeking elites.
US research receives 20 percent more funding relative to Europe (2017 data). More funding means more science? On top of that I would guess a post doc in the US can find a nice job at a company way way easier than the same person in Europe for the same reason: there are more higher-tech US companies with more big money who need the smartest people in the world to work for them.
I would also guess more and more loss of buying power (inflation without increase in productivity) in general causes a carreer in academia to become less and less attractive relative to a carreer in the commercial sector. That goes for both Europe and the US I suppose.
Example: I'm in Europe with a bachelors degree working as a freelancer (engineer) and probably make 300 to 500 percent more than people who work their ass off for decades in academia. So yeah there's "curiosity" and "passion" to stay in academia, but there's also cold hard cash.
My experience involves really well funded research areas in e.g. Oxbridge, sometimes better funded than their US counterparts I have interacted with. So I don't think its only about funding, but how funding is allocated. EU funding has a winner-takes-it-all structure. A few groups get enormous grants and the rest get nothing. Ironically, these groups have questionable productivity. Whereas in the US, e.g. NIH has lots of small and mid-sized grants that are suitable for a junior academic.
Junior faculty openings also exhibit the same trend and are much more common in the US. Among all people I have met in EU Academia throughout these years, only one person managed to progress to a faculty position. All others left Academia. Quite brutal, that figure should give policymakers some pause. In contrast, I know a few US academics that moved from PhD student to assistant and associate professor positions.
Exploiting postdocs without any promotion opportunities in sight is so common in EU that many countries are passing, or have already passed, laws to limit postdoc length. However, without more junior faculty openings and permanent staff scientist positions, I am not sure how this is going to work out.
My experience is different. The main advantage of the American Academia is the availability of entry-level faculty positions. Success rates for funding applications are also higher. On the other hand, PhD students and postdocs are less independent from their supervisors than in Europe. They lack the usual protections as employees you would expect in Europe, and it's not as easy for them to get independent funding. Students and postdocs are also paid better than in the US (relative to what they would get outside the academia).
I'm not sure about the status of academic freedom. Administrators, politicians, and donors seem to have more influence in the US, and the entire academia seems to be more politicized.
Differences (structure, funding, prestige) between institutes within Europe / USA are way larger than the differences between Europe versus USA.
What really matters in the end is whether an institute is able to attract “rockstars” in their field. Even better if these rockstars care about their institute and are willing to hire and develop young talent.
A single rockstar can elevate the prestige of an entire institution: look at Richard Sutton at University of Alberta, or Thomas Cech at Colorado.
This was my impression also, that there is a lot of difference how academia works across Europe. I'm not really an academic, but I went to a small international machine learning conference some years ago. The Norwegian postdocs got paid better than the French professor, apparently.
A French professor (eg CNRS researcher) is a civil servant, appointed for life, with substantial benefits such as pensions and absolute academic freedom. A postdoc in Norway has salary contingent on grants, limited to a few years, and is at the mercy of an advisor (a bad boss will destroy your career).
Making a few thousand euros more per month as a postdoc in Norway is nothing in comparison with a lifetime appointment at CNRS.
Competition for CNRS positions is as difficult as getting into a top tier faculty position in United States.
In Europe, academic freedom is limited because the structure we have resembles a very wide pyramid, with some minor differences across fields and countries. Junior professorships are more rare and more difficult to get into. The result is always the same, a full professor that controls his field locally and lots of expendable badly-paid postdocs working for him. Access to funding is also much more limited, which in turn restricts the capacity of said postdocs to pursue their own ideas, even while working under the umbrella of the professor.
In the US, tenure-track assistant professorships are much more common and requirements to apply are more flexible. Seed grants for junior faculty members are also common and not too hard to obtain. The result is a lot more freedom to explore. Basically, it is the same issue as with technology. EU suffers from over-regulation and control by some rent-seeking elites.