It's also usually NOT a rich parent. For example a big funder is NSF or NIH, these institutions grant money to labs with the expectation that they will perform research.
Don't think of it as being paid to go to class, think of it as a job where you work 40 hours a week (usually way more) doing reserach, then go to class, then on top of that help teach those classes through being a TA.
I am all in favor of cutting taxes on unearned income. However ironically, those most opposed to that also like to complain when it’s their unearned income being taxed as in the case of a stipend or fellowship.
And that's only because my parent's combined income was effectively $0, because neither of them could work due to severe disability. You can look at the income limits [1] and see that you basically have to be living in abject poverty in order to qualify.
So I'd advise you to actually experience it before telling others to read about it.
[1] https://www.hca.wa.gov/health-care-services-supports/apple-h...