At the same time though, what's the institution going to do? Teachers are already underpaid as it is, and you want them to manually check results from the websites their anti-plagiarism software finds to identify the owner and check if it's the student that submitted the work? Good luck with that, also given that websites are often not tied to single identifiable persons.
Professors at universities are not typically in the same financial boat as teachers at public K-12 schools. They usually earn in the range of 70k-80k (at least they did when I went to school 5+ years ago).
Also, they usually have undergrads who will do free manual labor for them.
