Pretty sure that's what he means. It's one of the more competitive academic positions.
Anecdote, but: I knew several math and physics PhD students. About half of the physics ones eventually obtained tenure track faculty positions in the US. Not a single math one did.
This gels with my experience (purdue physics/math grad 2011). It also reflected in the composition of staff for the departments. I think to field a robust math department you don't need the staff levels that you do to field a dual theoretical/experimental program in something like physics or chemistry.
e.g. at MIT the ratio of grad students in physics/math is 2.4 even though the undergraduate programs in Math (especially if you include Math+CompSci) are much greater
For the other departments, generally the university does not provide that funding anyway. The faculty members are expected to fund it themselves via grants. Although often for new faculty members, the university may promise one or two years of funding for labs. But again, since they get a cut of every grant that's coming in, they can afford to do so.
Anecdote, but: I knew several math and physics PhD students. About half of the physics ones eventually obtained tenure track faculty positions in the US. Not a single math one did.