>1) Master's degrees are frequently unfunded. PhDs in STEM are fully funded basically as a rule. PhDs in the humanities and social sciences are also often, or

>1) Master's degrees are frequently unfunded. PhDs in STEM are fully funded basically as a rule. PhDs in the humanities and social sciences are also often, or usually, fully funded as well; my sense has always been that for pretty much any academic-career-path field in the US, not being funded for a PhD is essentially an indication that the university doesn't actually want you there. Meanwhile, I think many simply don't offer Master's programs at all. One aspect of this is that in the US, PhD students can make up a significant part of the teaching staff at the university, with class structures that are heavily built around having large lectures by a professor and PhD students who do quite a bit of the more one-on-one instruction. So departments with many general education requirement classes, like History, can actually end up having a significant amount of funding for PhD students.