his is because i’m mildly certain that most of these TAs aren’t hired as TAs, because nobody really pays them. All PhD students, definitely all at Kampus Ochota, have a requirement to take a certain number of teaching internship hours, which is about 40-60 per year depending on field.

Depends on the course, but most TAs are PhD students, however some of the labs are also done by M.Sc. students hired on a contract (I was one!). PhD students don't get paid explicitly for teaching hours, it's part of their duties, but

but these grants are supposed to go for research, not for teaching

one of the main uses of grants is to hire PhD students! So having funds from research directly impacts the quantity and, perhaps more importantly, quality of PhDs, since ERC grants are very prestigious.

The tragic state of PhD students being on starvation salaries is a fact, but it's a wide systemic problem with the entire country's education. That being said, even with this "cheap labour source" you still can't run courses for thousands of people!