Correct. Public hospitals treat everyone without cost. I don't know why Pensador was charged 100 pesos. Was someone taking advantage of him?
During the bird flu (forget official name) crisis here some years ago the only medicine that could treat it was available at public hospitals. I got mine as a precaution at the Hospital Fernandez. A prescription was needed. There was no charge for the medicine.
On a related subject, does UBA charge foreign students anything in their undergraduate school? I believe it used to be totally free. Maybe is now. I think there are some charges for graduate school.