I am working in Germany now (in a "good" university) and I often visit top tier US universities.
Due having money, US universities at a similar relative rank have vastly bigger faculties, vastly better supply of researchers and usually better admin. And it is not even close. Network effects among researchers are much, much stronger.
Combine this with the fact that the German system has unecessary deficiencies. The appointment system is f'ed beyond repair and it is virtually impossible to offer positions to good prospective researchers. The "Mittlebau" lacks any and all good career track and is made up of disillusioned and hopeless people on 2-year successive contracts (and nowadays, it is missing entirely). And of course, there is no real tenure track, which means a lot of Profs are really bad and would have never gotten tenure in a meriocratic process.
Since we have a couple of privately funded places that do the US system here in Germany, we can see that it just simply works much better.
On the other hand, in terms of long term stability and the average quality of education, I agree that the US system has issues. Relying on inflated undergrad fees, especially from international student, seems dangerous in the long term.