From Princeton's policies, particularly the last sentence:
"Graduate study at Princeton, at both the doctoral and, in most cases, the master’s level, requires full-time commitment to study and research on the part of students. The Graduate School’s financial support structure, which extends throughout the length of the student’s program and ordinarily includes summers, is one indication of that requirement. Accordingly, the Graduate School considers employment beyond full fellowship, teaching or research support or its equivalent to be incompatible with full-time graduate study."[0]
It's even worse for international students. Under F1 visa, you can't work more than 20 hours on campus. However, all TA positions are deemed 20 hours of work. So you can't even work at the campus gym if you want.
This is not true at Princeton. Unless they are without funding, PhD students there commonly only work 10 hours per week (nominally) as TAs. The regular stipend is also generous compared to many other programs.
"This means that international students on a full AI or full AR appointment are not eligible for additional on-campus work, even if the Graduate School employment policy would otherwise allow it."
How can they say this, and then also ask their graduate students to teach? They're contradicting themselves.
Your comment is unrealistic and even absurd to the majority of those going through the PhD threadmill.
It's like saying you can dunk a basketball if you'd want to. Sure, show me LeBron James and how easy it is for him, but for those of us who aren't benefitting from abnormal competitive advantages then it's not that realistic.
How many people are lucky enough to be able to not only work a full-time job that pays the bills and is close enough to grad school and also be able to be in a field where literally part-time amateurs can do all the required academic work to write papers, a whole dissertation and defend a decent thesis? And in the end do well enough to aspire to have a career in your field of research?
You have a better chance of dunking on LeBron James.
"Let them eat cake."
Research is already a full time job.