As an aside, back in the good ol' days, students paid their instructors directly, out of pocket. You can damn well bet more than "near-zero" effort would be applied in that case.

Anyway, society spends a lot of effort supporting students, from scholarships and tax exemptions to the social beliefs that allow the random person to spend several years doing nothing apparently productive without censure. But all that only applies to students actually enrolled---non-guerrilla students. Guerrilla studenting, as it was in the past, would only be the province of the idly wealthy. That, I think, is why no one tries that route.