I think PhDs in the hard sciences do have low salaries. I was also surprised to read on the APA website that research psychologists start higher than clinical psychologists. I always thought most research jobs paid relatively low since they are so competitive.

There's funding issues, but sometimes I think its the fault of the researchers themselves, because universities can limit the slots in their programs if they wanted too I suppose. Just like medical doctors do, which keeps their salaries higher through their management of the supply side of physician labor.