I really don’t think this is an accurate depiction of university education. Yes, some profs are attracted to the research support of a university and are less invested in teaching. But that’s not a fair generalization of university professors. I know many professors at large universities who are deeply invested in teaching. And while it’s true that intro-level classes at universities might be more large lectures than small seminars, more advanced students have access to more small classes (no TAs) as they get into the upper-level coursework in their majors. Some universities have enrollment caps across the board (I’m at Master’s-level university, so we have few TAs, and my intro-level classes are capped at 35). Sure, the small-class experience starts earlier at a LAC, and LACs tend to hire faculty who are on board with their educational models and eager to place teaching on par with research. I’m very much pro-LAC, but it’s not fair to caricature university education like you have.
By the way – a TAship is essentially a teaching apprenticeship for graduate students, who don’t have the kind of training that student teaching offers for K-12 teachers. It’s as essential to their professional development as their research is, given that most Ph.D.s who are lucky enough to find jobs can expect to end up in institutions that are more teaching-intensive than their R1 grad schools. So rather than knock TAs, we might instead see their work as as crucial to the wider project of promoting excellent college-level teaching.