You can "default" on student loans, but in the United States government will garnish your wages and tax refunds at a much higher rate than Oregon's proposed 3%, not to mention all the harassment and extra fees that go along with debt collection. I agree, really. I think education should be completely free. But from an economic oppression standpoint Oregon's plan is a massive improvement. You're not permanently stuck with a debt that may be impossible to pay off, the payments are totally determined by your circumstances. However, I would be happier if it was progressive rather than flat.You can legally default on loans. You would be evading taxes if you didn't pay these.
IMO it seems like a fix for a symptom, that allows the problem to continue.