> master's in Wildlife Conservation
I wasn't aware that there was such a program. Anyway, there's a huge difference between Masters and PhD.
> These two actions are required.
The first, anyway. ;-)
But you seem to be missing the point. Professors are required to teach the graduate students, but the graduate admissions committee isn't required to admit any specific person or type of person. The professors get to choose who they want to teach and advise.
> These actions are not required
What's your point? Professors generally want to do these things. They need teaching assistants, they need lab assistants, they need research assistants. Professors recommend their advisees for jobs, just like the professors' professors recommended them for jobs when they were advisees; that's what you do, and what you want to do to futher your own reputation as a professor.
> It's not ridiculous when there's such an obvious institutional incentive, even if it makes their personal lives a little more difficult.
Universities are not rigidly hierarchical. Academic departments and tenured professors have a lot of power and independence. They actually don't have to sacrifice their personal lives for the sake of some administrator's goal.
> Also, you seem to be making an argument that out-of-state or international students are less capable than in-state students
Not at all. In fact, admitting in-state students is not particularly common in elite PhD programs, even at state universities. The reason has nothing to do with tuition and everything to do with competition: the admissions committee is free to pick the best applicants from wherever. I already mentioned this in an earlier comment: "The difference is that in graduate school, there's little or no bias in favor of in-state candidates, whereas for state universities, it's basically their mission statement to make dedicated space for in-state undergraduates."
I also said, "Many graduate students get tuition waivers, so this [tuition] is largely irrelevant."