It's safe to say your experience is highly atypical. Even if a grad student's stipend is not funded on an RA for their research, the research still costs money. It is certainly funded from somewhere, and it's not coming from the tuition. It's almost always the PI's grant. And that means your research is on a specific problem.
I can't speak to what your experience is, but what I am saying here is typical in US universities.
I can't speak to what your experience is, but what I am saying here is typical in US universities.