@Cue7 to Penn undergrads who enjoyed having 95% of their classes taught by Penn faculty, it makes perfect sense.
https://www.college.upenn.edu/prospective/faculty
"You have undoubtedly investigated other prestigious universities who also have fantastic professors, but Penn is unique in one notable way: All of our faculty teach undergraduates. That’s pretty unheard of. We don’t hire faculty, no matter how brilliant, who aren’t interested in the teaching mission of the College of Arts and Sciences.
In the College at Penn, 95% of courses are taught by faculty, not by graduate students, so you will get to know your professors…And, by the way, when you do encounter a graduate student as a teaching assistant or instructor, you won’t be disappointed. They lead discussion sections of large lectures called recitations and assist professors in grading, and grad students in the School of Arts and Sciences will be the Ivy League faculty of tomorrow, so many undergraduates find they are both knowledgeable and accessible."
I don’t know how Penn gives its grad students all of the advantages they need to go on to be great professors and yet they do! Penn’s grad students are hot commodities on the academic market even though the undergrads will very rarely interface with them in a substantive way. A recitation here, an exam grade there-- sure! I think I had perhaps 3 teaching assistants in all of my time at Penn. I still keep in touch with one and she’s enjoying her current teaching gig at Yale quite a bit.