That's not quite right 42. It is true that doctorate level programs do give out more assistance but not for professional programs such as for a JD or and MD. Law and medical students usually have to live off of loans which is why the average law student graduates with around $90,000 worth of debt and the average medical students has around $200,000. I made it through law school by getting TA positions in the political science department because there were not enough MA and Ph.D. students to fill all of the positions. It depends on the school, but many programs offer significant financial aid (real financial aid, not loans) to help out their master students.
Unfortunately, for someone in the social sciences, humanities, or english, getting grants, fellowships, scholarships, and other such aid is more difficult then if someone is in a science or engineering program (where they seem to throw money at all their graduate students).