[jrochkind1]

My impression is that humanities PhD students in the U.S. tend to be fully funded as well, although with smaller stipends than STEM PhD students.

I'm not sure where the OP gets the idea that PhD students in the U.S. usually have to pay their own way entirely and do not receive employment benefits (healthcare etc).

Humanities PhD students in the U.S. probably do have somewhat greater leeway in choosing/defining their projects, although they still need to pick one that their advisor approves and is comfortable with.