> A university spends less money on salaries by having a small number of professors with huge labs and armies of PhDs rather than a larger number of professors
It's also worth pointing out that this is pretty necessary from the lab's point of view, especially in some of the more high-end labs: PIs (in my experience, anyway) are frequently spending >90% of their time just writing grant proposals and dealing with the funding side of things.
There's very little time for them to do anything besides the funding circuit, and so the actual research part falls to graduate students and postdocs: People who obviously have less experience as professional researchers (and thus many more of them are required).
It's also worth pointing out that this is pretty necessary from the lab's point of view, especially in some of the more high-end labs: PIs (in my experience, anyway) are frequently spending >90% of their time just writing grant proposals and dealing with the funding side of things.
There's very little time for them to do anything besides the funding circuit, and so the actual research part falls to graduate students and postdocs: People who obviously have less experience as professional researchers (and thus many more of them are required).