[jltsiren]

The US spends less on academic research than the OECD average. See, for example, https://ncses.nsf.gov/pubs/nsb202326/academic-r-d-internatio...

From a European perspective, the most noticeable sign of this is the scarcity of postdocs at American universities. Some fields and individual labs are better funded, but on the average, the universities lean heavily on students doing the actual research.

[drnick1]

Because postdocs are basically slavery. The expectation here is that after a top Ph.D. (which tend to be longer than in Europe), you get a real academic job (assistant professor).

[jltsiren]

You have a few misconceptions.

The actual expectation is that after finishing PhD, you take a journeyman position, where you can practice the skills needed in an academic career and gradually gain independence while being mentored by a senior academic. Then, if you were successful, you get a permanent position. The postdoc path fails, as there is no clear path to a permanent position. The assistant professor path fails, because the funding system requires you to become a manager without sufficient experience.

European PhDs vary in duration. The most common system is 3+2+4 years for bachelor's + master's + PhD, which is not that different from the American 4+5 years for bachelor's + PhD. (Those are nominal durations, and actual studies usually take longer.)

In most European countries, a postdoc is a nice enough middle-class job. If you are interested in an academic career after finishing PhD, you have good chances of getting a postdoc position. The real bottleneck comes after the postdoc stage, as faculty positions are scarce in most European universities.